Having experience of contractors of one sort of another for over 30 years, I’m always put off by any company that rubbishes another’s work so, if they any good they don’t need to rubbish a competitor; personally, I’d be wary of both!
With most installers buying in from larger factories nowadays, it’s down to the quality of the installation & after sales service that matters. Compare the quality of the windows & judge the service offered before you buy; things like internal glazing beads (most are these days), the hinges, jam locks, locking mechanism, frame welding/internal reinforcing - grab the open window top & bottom & see how easy it is to twist it out of shape. Obviously make sure they are FENSA & that you get a certificate but do they also include an independent 10 year warranty, do they include trickle vents & new window boards & make sure they will make good any mortar/plaster they disturb. Never pay more than 20% up front (offer 10% if they will accept it) & don’t pay the balance until you’re completely satisfied.
I got quotes from around 10 local installers & looked in detail at 3 of them. The products were of similar quality, I think one was in fact Swift but the other 2 used Rahau units. If it’s the whole property you doing, it’s likely to be a lot of your hard earned cash so be a pest & a pain, then judge them by how well they respond! If they are any good, they will pander you & remain polite & calm, even if they are cursing you under their breath; I walked away from 2 who didn’t measure up on this test! Then ask to visit a couple of their previous customers, if they are confident of their work they will be only too pleased to arrange this for you. Price difference was negligible in my case & I settled on the company I felt most comfortable with (Rahau, units). They had to come back a couple of times to make adjustments but 12 months later, I am still very pleased with the work.
