No, asking for a refund from AAMCO certainly seems reasonable if the wrong part was used. The correct part should have been fairly easy to determine based on the VIN, engine size, transmission, etc.
If they will not refund your money then you can sue them in Small Claims Court although you will have to call the mechanic from AAA as an expert witness.
In small claims court you can represent yourself although, in this type of case, you can ask the court to award attorney's fees to you if you decide you want to hire an attorney.If you choose to represent yourself I would highly recommend you read up on the process as well as some other legal process. Most people who lose their small claims cases do so because they do not take the time to learn what they are doing and what is involved. If you decide to represent yourself go to
and pick up the ebooks on Small Claims Court, Discovery, and Trial Objections. Those three are both inexpensive and very comprehensive as far as their coverage in addition, they are ebooks which are updated regularly and don't have a lot of unnecessary information put in there just to make the book longer.
If your question has been answered then I'd offer my best wishes to you and ask that you please not forget to leave a 5 Star Positive Rating so I receive credit for my work. Of course, please feel free to ask any follow-up questions in this thread. I want to be sure all of your questions are answered.