I will be paying for absa mistakes

Absa debit order not done due to internal banking issue. Consultant called and advised me of this- pro-active. Debit order eventually went off on 9th jan. This implies that I will pay interest for their problem. Low and behold I now receive a registered letter telling me I am in arrears. Who will pay for this - me once again. It also contained insulting wording about debt counseling, itc , hand bank asset etc. This is poor service and I expect a writing apology soonest.