The dishwasher door was fitted with a plastic striker. It obviously wasn't meant to last, and eventually broke. This meant that the door would not shut properly, so I couldn't use the dishwasher.

I pulled out the dishwasher a little to expose the screw on the striker, (located on top of the dishwasher. The annoying thing was, it wasn't a regular screw, so unfortunately I had to go out and buy a torx screwdriver (which cost more than the new striker). It would have been so much quicker, and cost effective, if it had been a normal screw. Anyway, I completed the job and pushed the dishwasher back into place.