Door catch not closing properly?

I have a Hotpoint BFI 680 purchased less than 3 years ago. The door does not shut properly, it does not "click" and if you open it to add another item when the cycle is in progress the machine does not switch off.
We heard a noise when the dishwasher was not being used and thought a glass or cup had fallen but that wasn't the case. It was then that we found the door wouldn't shut properly, could it be that there is something inside the door shell that has "snapped" and could we repair it ourself. If so what could it be?
Many thanks