I bought an older house and decided to have wood flooring installed in the sunken living room (on concrete slab). Before installing the flooring my contractor said there was a spot that was not level, he charged me $400.00 to level the spot before he would install the wood flooring (not laminate). I paid him to level the spot and he installed all but the last two feet wide and twenty feet long section. Within the first week the floor buckled up over that spot. He came back and removed the flooring over the supposed leveled spot and said I must have a water leak. He now wants $500.00 more to replace the flooring over that spot, nothing about even finishing the job (the 2′x20′ section). From everything I’ve read in researching probable causes for this problem, it seems that he didn’t install properly. The spot was NOT leveled and there are uneven levels of concrete where he “leveled” the spot. When he removed the few planks of buckled flooring, the pieces left are cracking if you step on them, where the concrete is unleveled and there is nothing under to support it. I can find no signs of a water leak. What can I do to make the contractor fix and complete the job right? How do I prove it was installers error and not the supposed water leak?