Hi Debbie,
This is a common fault and is 99% the thermostat kit that needs replacing. They come as a pair and are located above the heater element behind the rear cover - just a matter of replacing about a dozen screws. You need part number 1701583:
http://www.ukapplianceparts.com/laundry.asp?search_fd3=Thermostat%20Kits&search_fd4=creda&multisearch_fd4=5
Lee.
December 2006