the house leaks

Yesterday my new house leaks on the new extension of the car porch. I was there during the heavy downpour. And I also found out that one of the drains is clogged with sand. I tried digging it but it didnt help. Today I will try to look at it again. I think this is the fault of the developer's workers and also lack of supervision. This is the attitude of the person responsible. Called the contractor of the problem on the leak. Anyway he hasnt finished his work yet.