Consumer Redressal

i have done waterproofing at my rsidence thru dr fixit approved contractor, but he has poor quality work, walls started leaking during rainy season, i informed contractor, he visited, applied some solution but the problem is still there, moreover till date he has not issued me Warranty Letter which he has to issue right after the completion of work, i have written to company also but even they are giving false assurances hence am approaching you, your prompt action and co-operation in this matter will be highly appreciated as these companies think that they are answerable to no one ?