Unauthorised Debit Order

in April/May I had a query relating to my debit order amount being different, despite that I had a contract signed with Multichoice for the price lock option. Eventually on 27 June 17 the query was resolved whereby I was contacted and a conclusion reached whereby the contract would end in August and no payment would be deducted for that month. Despite this the debit order was processed, returned by myself and again deducted in September. I did make a call to the call centre and was promised that a representative from the correct department would be returning my call to no avail. Please have the issue resolved as I am tired of spending and wasting time on this?