Endurance Auto Warranties not paying Also known as ApexWarranties Noy paying for repairs flagrantly denying my claim. Northbrook Illinois

I bought the top line warranty from Endurance and was assured they were a good , trustworthy company.  The covered  car developed a vibration at interstate speeds.  I took it to the Hyundai dealership. and they had the Endurance rep diagnose the problem.  He misdiagnosed the problem. He said it was the driveshaft because it was shaking at the rear of the transmission.     He had them replace the driveshaft which was not the problem.   I I immediately took it back as soon as I found it was still vibrating which was the first time i drove it on the interstate.  Now Endurance refuses to replace the transmission which is the rep's latest diagnosis.  They say they won't fix it because I drove it and ruined the trans.  Ihat is not possible  with the low miles I drove it.  I have spoken with several people  at Endurance and they literally try to play stupid and say they will stand by the orogonal diagnosis which was wrong.  So I am having to pay $6000