My dishwasher won't wash the dishes?

I have a diplomat integrated dishwasher that has stopped washing the dishes. The water comes through but the tablet falls out and it is still there when the cycle is finished. I have tried cleaning the dishwasher, new salt added and checked that nothing is blocked on the washers etc but still no joy. It is about 18 months old and have been told I will be charged anything from £70 to £90 for a call out repair, which I don't want to do. Many thanks