Consumer Redressal

I have purchased my home C block F1 from Anandham Builders, Chennai in October 2009. At time of May 2010, ground floor house owner came to my home with the builder and told “ there was a leakage and needs to repair in my bathroom” and they did the same, but my bath room tiles got damaged heavily. Now yesterday May 12th Sunday 2013 my ground floor owner started to complain about the leakage issue , and I don’t know how to handle now. As my engineer says the leakage from the inter pipe common to both, its really high cost matter. But they are not ready to contribute and keep blaming me and take care of full cost. Also they have maintained their Electric meter where my bath room pies joining and leakage is happening there. Can I approach the builder to repair with free of cost? If as per the law if builder is not responsible then please advise how can I claim the part of amount with my ground floor mate with a mutual agreement 50 to 50% and both responsible for future cause?