A while back I lost a dispute against someone who had paid for my service, he basically had claimed that he doesn't recall sending the money to me which is basically saying he was hacked. Anyway, my paypal account was put into a negative balance, I had to cancel my debit card so PayPal couldn't withdraw money from it. I received a lot of calls from them asking for £500 and that I've got 30 days to pay it back, even after 30 days they still continued to call me. I did try and sort it out and told them what happened, I even showed them proof that I was legit but obviously they had refunded the customer and didn't care if i was right or wrong they just wanted their money back. Anyway, after all that I've finally received a letter from a debt collector company which is requesting the payment. What should I do? I'm certainly not paying it back. But if I refuse what will happen? I don't want my name blacklisted for 5 years.