Bad service

I settled my account in December 2020. From 1st of February 2021 they phone me about my account that is in arrears. According to them I still owe them R147. In December I phone their head office for a settlement amount and paid that amount. Now they want service fees of me. What service fees? What service is there if the account is paid in full ? When I ask the lady who phoned me, she got an attitude and got nasty. Is that the way you handle good customers.