I appear to have solved this problem. Firstly I slightly adjusted the door catch on the actual machine, the strong wire bit, outwards. Then I undid the screws on the top part of the door exposing the electrics of the dial and door micro switch. I noticed that the microswitch (the small metal part pushed in and let out by the plastic arm rotated when opening and shutting the door) was dirty or rusty. I sprayed a little WD40 on this and played with the door catch a few times. I then screwed everything back in to place and the machine works perfectly. Easy and quick and a lot cheaper than the £80 I had just been quoted by a service person to come and change the switch mechanism as he called it!