Bosch dishwasher ?

My dishwasher (Bosch Exxcel) keeps going into overflow mode, I tilt it back and drains it will then nearly complete a cycle, as it's nearing the end of the cycle the time remaining will increase from say 30 minutes back to 60 minutes and go back into drain mode. The pump will stay on if I open the door and the rinse aid light comes on just after the increase in time.