I have a 95 Audi 90 and for the past year I keep replacing the ignition coil. I have no idea what is causing the ignition to stop working. It happens randomly with no sign of anything happening. I just turn the car off and then it will not crank after. I change the ignition and it works. I have gone through 5 and my car is now broken down again with the same affects. I have no idea if something is burning out the contacts or what. Any feedback is helpful, Im going crazy trying to figure this out.

Please Help
Thank You