受contractor欺負， 怎麽辦？

hired a roofer to repair my roof. I paid him $525 for replace the flashing around the chimney. Surprisingly, the new flashing causes more leaks than my old one. I called the contractor to fix it. He tried to seal it, but it did not work. I called him again, and he told me not to call him any more, otherwise he would prosecute me. I am really upset by his threat.

What should I do? Can I sue him for breach of contract and get my money back so that I can hire a different contactor?

TIA