Last week, I brought my 2010 Chevy Malibu to a mechanic. The check engine light was on, the temperature gauge was stuck at the minimum, and the A/C was not functioning. They looked at my car for free, and then said that there would be a $149.99 fee for further testing to diagnose the issue. I said okay. They called me back and said that I need a new thermostat and a coolant flush. I was told that my total would be $681 if I chose to fix it. I did.

Let me state that I know nothing about cars at all. Its a foreign language to me. I paid for the fix because I didn't know any better.

Fast forward to the next day; my check engine light is on, the temperature gauge is at the minimum, and my A/C isn't working. I told my girlfriends dad about what was going on because he knows quite a bit about cars. He went out and bought a coolant temperature sensor for $17.99 and replaced it in about 20-30 minutes. The problem is now fixed.

I called the mechanic to inform them that they did not fix my issue, and that I had done it myself, and they just told me "That's good" and followed it up with a "Have a good day." I was planning on asking for at least a partial refund or reimbursement, but I didn't even have a chance to do so.

Is this allowed? They basically just took my money and ran with it. My main argument here is that I paid $149.99 for them to diagnose the issue, and it was improperly diagnosed.