Car insurance windscreen question

[notorious]

Please explain me. Situation: I'm insured with Aviva, my A8 has heated windscreen and I want to understand what exactly happens when I need to change it when it breaks by wayward stone.

Heated windscreen from Audi costs about £600. Proper labour costs about £150, so about £750 in total if I do it privately. This is how much Aviva should reimburse me if I break windscreen. Right? No wrong. I called Aviva and they said they have arrangement with Autoglass and they basically compensate Autoglass only £110 for each windscreen change. £75 for windscreen part and the rest for labour. Obviously, this is not what I want. I want genuine Audi heated windscreen and I want to control any part on labour process, including what fillers and primers they use.

In my particular case Aviva offered to compensates me £110 cash and I can pay delta from my own pocket.

Question: Where the right people insure cars so when it comes to windscreen change insurance company pays for: 1. Expensive genuine Audi parts. 2. Private labour. No autoglass.

Maybe I'm an idiot.