Yes, it can be frustrating on these multi-airline itineraries, especially if the only way to get ticketed all the way to where you're going is using an airline that isn't a "full partner" (e.g. same-alliance member). The average customer shouldn't be expected to know all this.

In almost all cases, though, it's not a violation of any contract. Usually the airline has language like "baggage policies and fees may differ if your flight is operated by another airline," somewhere on their website's "baggage info" page.

There's language like that on Continental's "Checked Baggage Fees" page: http://www.continental.com/web/en-US.../checkbag.aspx.

"What if I am connecting onto a codeshare or Star Alliance partner?

When a customer travels on a codeshare flight or on an aircraft operated by a Star Alliance member airline, then the policy regarding checked bags follows the rules determined by the originating operating carrier."

Of course, since you bought on the phone, it's entirely reasonable for you never to have read the website. If the agent didn't disclose this policy, perhaps you could request a courtesy adjustment from CO. I don't know if you'd get it, but a politely worded, succinct letter to CO might be worth it.

I'd let go of the "two agents of each airline to say that I would have to take it up with the other airline" and contract violation stuff - the first is reasonable - Island Air has no reason to know or care about CO's fee policy and no obligation to be your advocate with CO, and vice-versa for CO with them. The second isn't true - nothing was violated, except the old standards of air travel courtesies, customer-friendly policies, and built-in amenities. Unfortunately that's not the world of any of the airlines these days. One way or another, they're charging fees wherever they can.

Even Southwest - they're just rolling them into much higher fares than everybody else while hiding their fares only on their own website so nobody can easily compare them with competitors all at once. I've never seen a WN fare less than $50-150 more than a UA, US, CO, DL fare for any of my routes that are in/out of WN-major cities, on 7-30 day advance bookings. Big deal that 2 bags are free.

Good luck with future travels, and keep participating in FT - lots of great people and good info to pick up here.