"Call your insurer" is the stock answer if you're comprehensively insured. Your inbound call gets switched to the prevailing
nominated repairer, usually one of the big names.
In order for one of these companies to bag such a deal, the bottom line is usually price; most of these 'contracts' are swayed with an 'average invoice value' deal and if you're keen on getting that insurer's business you're going to have to beat the previous repairer's AIV deal. This has been going on for quite some time and that AIV is now lower than a snake's belly.
With very tight profit margins, the emphasis is very much on volume. The only other option to maximise the bottom line is to buy glass/parts cheap. Cue: aftermarket glass from all over the globe; some is OK, some is not. Generally speaking, the best quality is OEM (car manufacturer branded). If a piece of glass does not bear the car manufacturer's identifying crest/emblem/logo, it is not genuine. Even if the glass manufacturer is the same, it does not necessarily mean it is the same 'unstamped' glass. In fact, it rarely ever is. There are only a few examples of branded/non-branded glass being the same product.
More
here.
The aftermarket copies are much, much cheaper. Do the Pepsi challenge against a genuine version and you will usually see why it is so.
Re insurance. A lot of the terms and conditions - especially for non contracted repairers - require that the 'best available parts and materials are used'.
When a repairer tries to charge you a supplement for genuine parts, is there anything in your policy which states this? No? Funny that, because there rarely ever is, so under what terms are you 'required' to pay any extra? It's an insurance policy which indemnifies you for loss. At what point does it stipulate that the
cheapest available parts will be used unless you pay extra? These are salient points which should be made reasonably clear before inception. A proposing insurer is required to do this.
