Doppel, I really feel bad for what happened, but it is very hard to 'beat' the insurance company at their game.

Personally, what I think will happen is that they will return the car to you in the condition it was in, minus the film, as that would be considered an 'add-on', or 'aftermarket' part. Cars don't come with these film from the factory. It was applied to you afterwards. (even if it was dealer installed, it is an optional accessory/ add-on). So the insurance argument will be like: "Yes, we will repair your car's fender/ bumper to like new condition, which we did". and "Yes, we will apply the film for you, but we will not pay for the rental/ waiting period". why? because it is not their responsibility that the paint needs to cure, and secondly, it is considered an aftermarket / add on part.

Don't get me wrong. I am not defending the insurance company. However, do you have something in writing that they will cover the rental for xxx days? When I had my accident, i spoke with the adjuster and they will give you xx days of rental. If you needed more days, you would call in, and they will approve / extend. If you keep the car without telling the insurance, it's on you. When my car was totalled, they gave me 1 week rental to look over the paperwork and assess value. As the rental return day was approaching, I called them to see if they were ready. They were not, so we extended it for another week, etc. That's how it usually works. Lots of calling and following up and a major pain in the ass.

Now you claim that someone from the insurance company said it was ok for the paint protection to be applied. However that person may have not been knowledgeable enough to know that the paint needed to cure. Granted, that's on them. However, that does not mean he gave the ok for another month of rental. The insurance will still pay for the paint protection, but on their schedule. i.e. when you are ready to have it put on. That's what you need to fight them on.

It will be a hard battle, not totally impossible, but here are what's again each party:

Insurance:
they promised (verbally?) to put paint protection on the car. Their ignorance of the time of curing is against them and not your fault

You:
you may not have an approval in writing that they allowed you to extend the rental.
your paint protection will be treated as an 'add on accessory', like wheels


What I would do is start writing letters to the insurance company. Sometimes it works, sometimes it doesn't, but will give you an idea what to do next. I would say leave legal option as a last resort as insurance companies are usually lawyered up the ass.....