ah cheers fellas, sounds like the best solutions are the easiest/cheapest, but will have to wait till tomorrow now though as it is p*ssing it down outside!!

this definitely sounds like the problem as i have now noticed that the front and rear doors lock differently, not by much, but one of the rear doors locks about half a second after the fronts. all other cars i have had with central locking lock and unlock at the same time.

also the tailgate needs a good few presses on the key fob to open(there is a brand new battery in the key). could this be the same problem?