I agree with you on a high level that this was not handled well by Thrifty and that you should not be subject to an experience like this.

However, as someone with experience in the industry and with a lot of experience with Thrifty, I understand the nuances of what's going on here and why it's happening.

For one, you're working with a local franchise. Franchises operate autonomously from the corporate brand, within the limited guidelines of the franchise agreement. Unless otherwise specified by the franchise agreement, the only major threat a franchisee faces is the loss of their franchise license, and it would take a lot more than a few customer complaints about reservations not being honored to cause that.

Two, the rental industry simply isn't set up with a path to resolve issues with uncooperative locations. Thrifty (and, frankly, all rental companies) need to optimize and publish their procedures for oversale situations. There should be some key points:

• Reservations are binding and must be honored unless the terms are violated (renter does not meet qualifications, shows up outside a [needs-to-be-published] availability window, etc.)
• If the reserved vehicle is unavailable, the next larger available vehicle must be offered at no additional charge
• If a rental location is not following these practices, there should be a defined escalation path, and people along that escalation path should be empowered to resolve issues and find/offer alternate solutions

Currently, those don't exist. There is a convention in the rental industry that reservations are to be honored and that an upgrade should be provided for free, but it is only a convention and is not written anywhere. There is also no escalation path beyond asking for a manager at the local counter--universally with all companies, phone reservation agents are unable to handle location-specific issues (they are only able to make/change/cancel reservations), and phone customer service agents are unable to assist with active rentals (only rentals that have been closed out and returned), so calling the corporate phone tree when it comes to dealing with issues at the rental counter is not a productive path (do note this is the case with all rental companies). I believe that needs to change, because when you end up with an uncooperative location (as in this case), you are basically taking it on faith that the corporate office will make things right, which, unfortunately, is not always a safe bet.

That said, this is FlyerTalk, and FlyerTalk is not a place to vent uselessly--it is a place to post questions and learn from experts who have lived through what you are encountering and can offer their advice for how to resolve issues. To that end, we here have posted our suggestions for how to fix what you encountered, in the event you had decided to try to resolve your issue or in the event a future person encountering this thread encounters the same kind of situation. Those points are:

• Arrive with a printed copy of your reservation printed directly off of the rental company's own website
• If the front-line agent is uncooperative, ask to speak to a manager then and there
• If an alternate option at an acceptable rate is not available, you should continue the rental process. If possible, sign the rental contract with a note that you are signing under protest. If the rental office is unwilling to give you a car at all, obtain a written note from the agent that they were unable to provide you a car (not likely they'll agree, but tell them you need it to file a travel insurance claim and they might be less opposed).
• Again, ask to speak with a manager upon return and attempt to resolve the issue then and there.
• After you have returned the vehicle, submit a brief, pithy complaint to the brand's main customer service department (i.e. an email form at Thrifty.com or Thrifty's 800# in the US).
• If the customer service department is unable to resolve the issue, escalate to the executive level (elliott.org publishes a lot of these, as I linked above)
• As a last-ditch effort, dispute the charge on your card. Maintain and submit copies of your original printed reservation confirmation along with (if possible) your signed rental agreement with the "under protest" note, which will assist with your defense.

The chances of getting some form of compensation are reasonably high if you follow this escalation path. If you cancel the transaction and go elsewhere, you are unlikely to receive any form of compensation, since there is no charge on which they can process a refund, and it would simply be your word against the location's. (That's why it's important to try to get a written note from the agent if you are forced to rent elsewhere because they simply have zero cars available.)

Do be aware, however, that with the Thrifty/Dollar/Hertz brand, at least, they are unable to compel non-US/Canada locations to provide an actual refund to your credit card. However, if the location itself does not agree to refund you, corporate customer care will issue you a customer service voucher that can be redeemed for a future rental. (Presumably they then back-bill the franchise for the cost of the voucher, though I am not certain.) It is less convenient than cash, but that's their procedure. (Previously, corporate would actually issue a check for foreign, non-corporate-owned locations, which they would presumably then bill the franchise for, but I have not seen or heard of that happening after the Hertz merger.)

Anyway, that's my advice for dealing with rental companies based on 15 years of experience in the industry on several different sides. It's the same with all of the brands; the customer service quality and response varies by company, but not significantly, and the same processes and limitations are in place with all of them (though some handle it better than others).

FWIW, if you do choose to "never use Thrifty again" (a rash and illogical decision to make based on one rogue franchise's actions when you did not even pursue the matter with Thrifty's corporate offices), be sure to also never use Dollar again and never use Hertz again, since they are all owned by the same organization (Hertz Global Holdings).

For that matter, you should probably also never use any of the brands operated by Avis Budget Group (Avis/Budget/Payless) or Enterprise Holdings, Inc. (Enterprise/National/Alamo), because complaints about those companies are all over FlyerTalk and review sites like Yelp and TripAdvisor. Probably best to just stick to taxis wherever you travel...