contracted with a contractor to build onto my home, and the contract states it will take 6-10 weeks. been at our hourse 18 weeks do I have to pay?

contractor has had to re do many things because worker did it incorrectly first time. We paid the first 2 installments we only owe $4000. Contractor has asked for last of money, but the dry space is still leaking after being redone 4 times. Many mistakes throughout the time they have been at our house, including roof having to be removed because the pitch was not correct. Sub floor not nailed to beams, insulation placed upside down, boards placed so that they cupped, deck railings not spaced per code, deck railing not nailed, many boards on deck not nailed down. We will pay if need to but at this point we feel like we deserve a rebate for the inconviences they have placed on our lives.