im currently fitting my kitchen. its a first time. while installing one of the cabinets, ive come accross an issue. I just wanted some advice on what's the best way around my problem: the base unit has been levelled using a spirit level in all directions. however, when i put the back of the base unit up against the wall, i noticed that the wall slopes away from the back of the cabinet. So the bottom part of the back of the cabinet meets with the wall, however as you go up the cabinet the wall slopes away, leaving about 15mm between the wall and the top most part of the back of the cabinet. hence, would it be best to modify the back of my cabinet to match the wall profile or modify the plaster on the wall and straighten it out?