Woolies acc

I am very unhappy with Woolies. My account was in arrears last year, but was sorted before year end. I am currently not in arrears, and have made my monthly payments, but I keep on getting messages from their lawyers demanding I pay my account. I have been sending proof of payments to the Manager, but they keep on demanding payments from me....wen I try explaining that I made payments, I get told to contact Woolies directly....I'm so not happy, and not sure who can fix this