Poor Service of debt collection

Sometimes one can think this are **********.

I have been owing fnb , and they send me threats SMS'ses we tried to cooperate with them. Last year march we have been asked to make payment, we did that and it turned out that one of their staff members has provided us with the wrong reference (whose fault is that, tend to have made payment into someone's credit account.

We then made arrangements again and made payment into the provided account number, still they sending us messages stating we have not paid as agreed,

This is so stressful, while we willing to settle but there's no help at all