P7M8

Brought my new to me 2011 Shelby in for window tinting. They were prepping the rear glass for the tint and the defroster lines pretty much all flaked off. While this is a 7 year old car, it was garage kept and had only 2200 miles on it when I got it two weeks ago.

Did Ford have an issue with bad defrosters where this was a problem?

They used a nylon pad that you would use to scrub pots. I questioned why they would use such an item but he assured me they've used this process for years and have had just a few instances of this happening.

Looking for guidance on how to proceed. The guy was very apologetic and while I offered to pay for the work he completed he refused to take my money. This local business has a good reputation.