Hi there - I have exactly the same problem with a Hotpoint that stills spins but stays cold. Now ordered two replacement thermostats (£6.99 espares) - each is attached by two wires and easy to replace. 90% chance of this being the problem - just make sure you put the right one in the right place (one will have a dot on the back). Good luck - will add update when done!
Iancambs
December 2008