Ariston Margherita A1635 problems. Wont empty water, please help!!?

Hi

We first had a problem with this machine a few days where the program dial kept going around, we have reset it after readin other people with similar problems on this website. Now it wont move onto the rinse/drain/spin program and the drum stays full. It makes a humming noise but doesnt do anything. Ive had it out and emptied it via the filter at the bottom, checked all the pipes etc. Does anybody have any idea what it could be? I dont know anything about washing machines but i presume there is some kind of pump that pumps the water out, maybe this has gone......but why would the program wheel not finish the wash? Any help would be greatly appreciated. Thanks in advance