AFRIHOST - Unsettled account that is paid in full!

I am being billed by Afrihost after 2 of their staff said that my account is settled. This happened after I canceled my service with afrihost. I sent back the router (paid for the collection) . There is now an additional R1200 on my account. My account has been paid in full as clearly stated on bank statements. 3 weeks later and no reponse!!