In addition to UA deciding that they no longer wish to do business with you, if you do want to take this to court or a regulatory complaint ensure that you read and understand rule 3(q) of the contract of carriage which includes the right for UA to collect their attorneys fees from you should you not strictly comply with the requirements.

I feel your pain, and it was a decision to make -- probably the right decision -- but UA is not obligated to pay the costs of that decision. You could have waited 6 hours and gotten a "free" result (or not) or you could cut your losses and have a more definite result, you chose the later and there were costs involved

There have been times where I have cut my losses and rented a car to get home. I expect (and UA has always provided) a refund for the services UA did not provide; I do not expect (nor is it reasonable under the terms a passenger agrees to with UA when purchasing a ticket) UA to pay for the consequences of my choice (i.e. rental car) made for my own expediency.