Door doesn't fit properly

My Mum bought a 600G single gas oven and has hardly used it as it is dangerous and unsafe. There is a gap at the top of the rubber seal around the door. Consequently, the oven loses heat through the top of the door and heats up the control switch. The flame goes out frequently and the oven never gets to the correct temperature because the heat is escaping. Apparently, there is no adjustment in the door hinges so the problem can't be fixed.