I recently got a 10.2ft glideroll roller door with a merlin 430r electric operator. I was going to get my builder to install it but he said it was better to get it done by a garage door dealer. The builder is widening my garage to enable the new door to be installed. It currently has a 7ft up and over door. The garage is approx 11.5ft wide and the door is approx 11ft long including the rods on each end so its going to be a bit of a squeeze.

I got 2 prices for installation; £205 and £280 incl vat. Does this sound reasonable or should I try to convince the builder to fit it? The building work to widen the garage had included fitting of a 9ft up and over door but I changed my mind and got a auto roller door. The builder has an auto roller door himself but he did not fit it. He thought it would come in "a million pieces" but the parts only consist of: the door, electric operator, 2 brackets and 2 metal guides and about 20 screws and bolts. Should I be safe and get a garage door dealer to install it? Is there anything important I should know?