I hired a tiling crew to install tile in my new house while I was away. When I returned, after about a day of using the toilet, shower, and sink, my toilet clogged up, eventually resulting in sewage coming up into my bathtub. I noticed what looked like thinset or grout in my sink and around the tub/shower drain, so I asked the contractor if they rinsed their tools and buckets in the sink, which he initially denied, but then suggested that it was possible that one of his crew may have improperly disposed of these materials. The contractor invited his plumber friend to come over to snake the toilet and the tub, which seemed to temporarily improve the drainage. But later that day, everything backed up again, so the contractor came over with a bottle of muriatic acid and poured it in the toilet. This has not yet freed things up, so the plumber is supposed to come over tomorrow to put a camera in the lines to see what is in there. The contractor is not admitting responsibility at this point, but said he will pay for the plumber if it is his materials that is determined to be responsible for the blockage. Any recommendations as to how to get this taken care of if it is a result of thinset or grout?