Personally I have a "free windscreen repair" ins policy.
a. My last car had a crack/stone chip on the passenger side .I could have had it repaired free but
I dont go for this "we can do an invisble repair with our super resin"(when it costs me nothing)
If my windscreen is cracked I dont want a repair. they can just put in a new one, I really dont care how invisible it is and I wouldnt be surprised if the ins was charged near the same amount.
Free windscreen replacement (no matter how often)is just that..Im not gonna take some resined up repair.
I also/didnt get the screen replaced over a 2 year period ,cos I knew I wasnt gonna keep the car that much longer.
Even tho the repair would have been free , I wasnt going to go for some money wasting repair, even if it wasnt my cash.
Your case.. can it be resin repaired?..
then if something happens to it again and the windscreen policy is in place ,he can get a new screen.
£300 for a mirror glass?
edit:a few years ago(last century
) my windscreen was replaced under insurance. Got the car and the screen was "clear". The original was tinted.. back it went.
A stone embedded in the screen sounds beyond the invisible repair capabilities , and too much to just leave.