Help. I decided to repair some broken tiles in my bathroom and felt the need to also remove some towel bars not being used. The tile was set in concrete and left a large hole (4"x4" tiles - so just the corner) and uneven surface. How do I fill the hole where the towel bars were so they are flush and stable to set new tile? See bathroom tile album for photos. photos//www.diynot.com/network/willgirl/albums/