The client I did work for is threatening me by reporting that "I have scammed him". The issue is that he gave me 3 tasks which I did well. Then he checked if everything worked, approved, and paid for. However, after about 2,5 months (today), he claims they don't work and asks me to redo everything. And he endlessly texts me it's my fault. I'm afraid of having negative feedback thus my work was done well. Can you help deal with the situation, please?