Your homepage opens with the range: eleven door styles, then nine window systems, then a finishes gallery. A visitor has to know what they want before the site is any use to them. The first question your showroom staff ask is whether it is a replacement or a new build, and that single question halves the range before anyone looks at a photo. Your site never asks it.
Second thing, and this is the one we would act on first. Buried on page four of your FAQ is that you take out the old frames, make good the plaster and take the waste away. Nobody in your market says that plainly. It is the reason someone chooses you over a cheaper quote, and it is currently a sentence a customer only finds if they were already sold.
Both of those are the same shape of problem: the thing that wins the sale in person is the thing the site keeps to itself.