Bad service from HiFi Corp Credit Department

My one account was handed over because they could not split the money between the two accounts although I have the same Customer Number on both Acc's. I was given a Complaint# 9000163767 and on enquiring just received an email that I should pay the Debt Company and to just continue paying the other Acc as normal. I did ask them to rectify the matter but their no care attitude is quite disgusting. I do have proof that both Acc's were paid in full every month. What do I do to clear my name ?