Ray Dennison Chevrolet

I got a truck from Ray *** Chevy 'bout a year and a half ago. Got the extended warranty too. Recently, the headlights started actin' up so I took it in for service. They told me it might not be covered under warranty. Next day, they called and said the previous owner installed an aftermarket conversion kit on the headlights and I wasn't told about it when I bought the truck. I argued that it's a safety issue and I was sold a defective product, so it should be covered under warranty. They said they'd have their GM tech look into it and call me back. Next day, they called and said they removed the aftermarket parts and returned the headlights to factory condition, but it wouldn't be covered under warranty. I never gave them permission to do any work without my approval. I made it clear that I didn't want any work done until they confirmed the problem and gave me a price to fix it. They did the work without my say-so and never gave me a confirmed diagnosis or price. Now, I gotta pay the bill or risk it goin' to collections. A) This should be covered under warranty and B) they shouldn't have done any work without my permission.