Ive got a shower which was emptying slowly and also filled up with water and gurgles when the sink was emptied. Ive managed to clean the waste pipe on the shower today and removed a load of hair etc and the shower water now runs away fine but the water from the sink is still filling the shower tray but empties as soon as the vacuum has gone i know its a vent blockage if it gurgles but what about filling up with water?