I'm with a different insurance company, but they give me free windscreens as well, i've had it replaced twice by them, same windscreen company you used. First time the plastic bit that sits on top of at the bottom of the windscreen got broken/cracked a little bit, not a big deal, its pretty old and dry, not really his fault. I was watching... 2nd time had no issues. It will be down to the individual installing the windscreen i guess. Insurance did say i could get it done anywhere and just send them the bill to be reimbursed but couldn't be stuffed, this way i didn't have to fork out the money at all.