Hi - we have put on one coat of Dulux Kitchen and Bathroom (in white) in our new bathroom. It is rubbish. It has gone on very patchily and you can see the roller marks. We put it on top of a cream homebase matt paint which painted by the previous owner. Question is what to do...sand it down??? What to use instad and what will give a smooth finish over the disastourous K and B?????