Hired architect and contractor for house construction

I hired a contractor and architect cow construction of a stilt +3 house. Now the roof has started leaking and also walls on 2 floors. During the time of construction I had insisted many times that I did not want any leakage and they assured me of the same. I was asked to put a water proof coat on roof at extra cost as per their advise. Now it's leaking badly and the person my architect directed me to is saying it is because of poor construction quality. The concrete mix was sub-standard and so on. He has quoted an estimate of Rs. 500000 to fix the issue. The house is only 3 years old. Can I sue the contractor and recover the cost of repairs from him? I feel they are at fault and want them to bear the cost of repairs