Worst accounts department and customer service

Does your accounts department even go to work? I rented a bottle of SureMix in December which was returned in January and no replacement bottle was taken, but without fail I still get charged monthly amounts for a bottle I do not have. I have tried on multiple occasions to email your "Customer Services" (with the proof of return), only to get an automated response with a query number but I never hear back, until I get sent my next months bill, charging me again for something I don't have. Now December comes and I would like to rent another Suremix but cannot because my account is apparently in arrears. Your service and accounts department is appalling.