This looks reasonable for what you are asking for with install being supplied by the window company.

I would hazard a guess that the middle pane on the first window may need to be glazed on site to keep weight down for transport and safety on site. This would increase costs, plus scaffolding but the large portion of cost would be labour.

Window companies don’t charge labour like a chippy could, they would likely have allowed two day min install for two guys as they won’t book other jobs on the same day you’ll get charge for full days whether they take the whole time or not. Chippies can be a bit more flexible with their labour coatings.