aluminium patio door

We've just had a new 3metre aluminium patio/slider door fitted. Intially when it was fitted they forgot to put in the rollers so it wouldn't open properly. They came back and fixed that now but the door is very stiff to try and push accross, even my husband finds it difficult, they have told us that its because of the size of the door and weight of glass etc and eventually it should loosen up a bit.

Anyone out there have expierence of this or are they trying to pull a fast one?!!!

It should roll smoothly, may take a little push to get it going, but once moving shouldn't take too much effort to keep it going. If you're getting constant resistance, they haven't fitted it properly.