Hi, the tiler I'm using is relatively new to the game. He tiled a bathroom and ensuite for me and did a good quality job. when he started to tile the kitchen he told me the floor was uneven in parts and he couldn't tile on it. I called the builder and the builder said that the tiler should build up the adhesive under some of the tiles so that the tiled floor comes out even. The tiler says he can't do this. I don't know whether it's down to inexperience or a genuine problem with how level the floor is. Does anyone have any suggestions on how to get around this problem?