Hi Niku,
yeah, we're finding that a lot of these companies are just scam artisits.
Whatta yer expect living in Brummy?! oops did i say that out loud?!
We've just had our windows re-done and a similar requirement to you was the 'Bay' window. Ours isn't curved but more 'square' so they break up the bay window into separate windows and count them individually. So our's became the main front 'window' and 2 side 'windows' making a total of 3. Then we had 4 more bedroom/bathroom windows done as well.
I researched quite alot of local suppliers and tradespeople in the window and conservatory business and got prices from quite a few places. I was very tempted by the 'warehouse' type supplier who measures up and gives good discounts and then says you can fit them yourself or they can do them.
In the end, I went 'high end' - to Anglian windows - their fitted price was only £400 quid more than a few other quotes I had, got the salesman in with the usual sales pitch - but i bargained him and said yes to all their 'sales incentives' (which is just sales crap really)
Managed to wangle 'free' window vents for all windows and my two south facing bathroom and bedroom windows, I had the Solar dark glass 'upgrade' thrown in. All the work was done meticulously, excellent fit and finish, 2 days like they said, no mess inside, all guarantees in place and I'm very happy - to me, worth spending the extra for peace of mind - anything of a concern, they'll be out to fix and seeing as they're a big company, an increased chance they'll still be around in some years time. Paid £3K for everything.
The 'warehouse' guy is based in Ascot, not sure if he'll cover your area for fitting, but maybe for supply. I can recommend our complete experience with Anglian, if I had to do it again, I'd certainly give them a call - all double glazing comes with the salesman at home thing though.. do your homework and ask for discounts all the way through and be forceful that you'll just get a price and compare elsewhere unless he really sorts you out a good price.
Cheers, DtM! West London & Slough UK!