Payment allocation

I am extremely upset. I made my normal EFT payment on the 30th November. I just received my sms stating my instalment due for this month is basically double my normal instalment. Logged into my online profile and saw my payment was reversed on their side and reflecting as account in arrears, yet the payment was made via EFT and NEVER returned to me. Double checked my bank statements to confirm this before phoning the accounts department. Lady I spoke to was quite rude and advised they had problems with their EFT system but it's now been corrected and payment been allocated. This is not the case when viewing my online statement. I don't really give a fly about your problems, all I know is this date is normally sent to the credit bureau and if my account reflects in arrears there is going to be hell to pay. I expect a confirmation in writing that there is no adverse credit info listed on my account