MY car door wont open and the central locking contantly locks and unlocks?

MY driver door is stuck. it wont open from the inside or out. The handle moves but its moving liek the your trying to open the door when its locked. The central locking jumps from lock to open on the other doors constanly untill they are closed. I took it to Kwik Fit and was told it cant be MOT till this is fixed but they said they cant fix it ( i know.. great). Does any one have any suggestions on this ?? I need to get it MOT'd.

Its a Citreon Saxo by the way.

Please help :(