I've had no problems with the 8 sets I purchased from https://www.whiterosewindows.co.uk about 7 years ago, but I do wish for a couple of them I'd chosen the the "blinds built into the glass" option
Edit: actually, I've just remembered, there was one small fix I made to every door. About 3 years in the handle on one of the often used doors started to feel a bit loose/sagging a bit. I removed it from the door to find the square hole that receives the door handle spindle had cracked and wasn't gripping it so well. It turned out that the spindle was (in my opinion) about the 20mm too short (when assembled the two handles plus spindle was about 20mm narrower than the thickness of the door). The spindle looked to have been fully located into one handle but wasn't really making good contact with the other handle. Had the spindle not been offset I reasoned it would have been fine. For this door a replaced with a longer spindle that made good contact with both handles past the cracked section, but for every other handle I removed them, poked a 10mm bit of foam to the bottom of each door handle hole and reassembled. This way all the spindles sat centrally rather than offset..
I asked for supply and fit on most of the door sets but for two I got a reduced rate at supply only because i wasn't ready to fit, and I fitted myself. They travelled over 100 miles to do the job;m, and from what the fitters said of where they worked they seemingly had a nearly national reach.
That was all many years ago and things may have changed but their prices were good and they were easy to work with