Hi, it sound like the sump hose is blocked,
to access the hose remove the left hand side panel & the bottom plastic kick strip at the front of the machine. Once the side panel has been removed you will see a plastic water chamber, at the bottom of the chamber there is a hose that goes into the sump of the dishwasher, this is the hose that will be blocked, remove, clean & refit hose.
hope this helps
www.candmdomesticappliances.co.uk, December 2009