Hi Diana We have same problem had it sorted Nov '06 and today its happened again. There is a filter at the back lower left hand side as I watched the engineer pull it out last time to unblock he had to unscrew something to get to it but it didn't look too difficult, once my washing is complete i'm going to give it a go myself as I'm not paying another £90 to get the engineer back again.
Hope this helps
Jenny, June 2007