Car Mechanic Won't Honor Warranty Help!

On Saturday I noticed my car was having trouble getting started. I would turn the key to start the ignition, but instead of starting up I would hear a single loud 'Clunk' noise. Through process of elimination I found out I had a bad starter.

I called several shops and finally got my car in for a diagnosis. I told the mechanic about my problem and after running a few test confirmed I needed a new starter.
So I paid him $400 parts/labor and 3 hours later my car was ready to go.

The next day (Sunday) I drive about 200 miles, fill my gas tank, turn on my car and.......nothing. Again, as I turned the ignition I would hear a loud 'Clunk' sound and my car wouldn't start. Shops are closed on Sunday so I cant call for help. Instead I try several minutes of cranking my key and eventually my car turns over and I drive straight home.

I called the mechanic shop the next day (Monday) and explained the same problem. They told me to bring the car in but since I was 200+ miles away and needed to start my car I instead took out their bad starter and went to several big name stores that would test it for free. All 3 places I went to confirmed the starter was bad and I needed a new one.

Since I could not afford another $400 fix I instead went to the local AutoZone, bought a brand new starter and put it in myself. My car now runs great with no more clunking noise!

I called the shop and told them what happened and the mechanic said that since I fixed the car myself and was not a certified auto mechanic that it voided the warranty and that they would not honor it.

My issue is that they sold me defective part and after only 2 days and 200 miles it died on me. Am I entitled to a refund? Are they allowed to sell defective parts and tell me its no longer their problem?
Can I take legal action!?
Asked Jul 26, 2016

TIP: If it's not your answer to this question, please click "Leave a Comment" button under the question to communicate with the question owner.