Bad service in accounts department

Truworths account department is messing with us. 2 months ago my payment was not allocated and I was informed that I have use an incorrect reference number, In future I must use the account number or ID number. I have been using my ID number and all of sudden payment is allocated again because I have use my ID number instead of account. Yet the past 2 months they were able to allocate with Id number. This is unacceptable . what is so difficult in allocating the payment. I assume now that interest is being charged on the account. I have made up my mind I am closing this account, I need this drama all the time.