This has happened to me in the past (5 years ago) with Admiral who I'm with again this year.
I don't have an issue with a non OPC screen as they are all made and tested to the required specs. What is a problem is that it's total pot luck as to whether you get a careful fitter who takes a bit of pride in his work, or Dwayne the party animal who was out clubbing til 3am the night before he fits your screen at 9am.
I used Autoglass up here in Newcastle and although the guy was a jobsworth he managed to scratch my colour coded ashtray lid. After much arguing with him and his boss I was refunded my £75 excess towards respraying the ashtray, which I didn't get done as it would have opened up a right can of worms I think. (Matching guards red etc).
What was also funny was the fact the fitter kept telling me over and over that "I don't get 911s me. Don't see the attraction". I'm not sure why he thought I'd be too bothered. I just wanted my screen fitted.
Oh and the first time they came they brought the wrong screen. I'd taken the day off work too. Not impressed.
If you don't choose Autowindscreens your insurer will have a list of companies they use, but you'll always be at the mercy of the fitter.
I'd try and contact Glassman on P'heads.
He's very good, based in the London area but may know a decent non-OPC fitter in your area, although they may still only want to fit an OPC screen.
OPC screens are generally about £800 and your insurer may let you pay the extra yourself. I personally would rather pay my £75 excess than about £600 but it's upto you
Good luck. Hopefully someone may have a better option. :thumb:
Edited to add - I've just noticed you're in Herts. Definitely ring Glassman for advice.
I have also used the Newcastle branch of Auto Windscreens and they were great but again it's pot luck as to the type of person you get.
Unfortunately we need to clarify things like windscreen renewal when taking out our policies, as by the time you realise, you're snookered.
As I've said I'm not particularly bothered about the make of glass, as long as it's fitted correctly.