Cancelling contract

i contacted Virgin mobile in May to cancel my contract and was told that i had to pay R534.00 directlry into an account given to me by the person on the phone to cancel my account .which i did the very same day i then tried to contact the accounts department to notify them that i had made payment as they requested for cancellation. Tried several times but was unable to. i then got debitted the next month for my contract as normal after i had requested a cancellation ,this has gone on till now .i have contact the accounts department again and only now have they put in a request to cancel my account six months down the line. The person in the accounts department said that they assumed that the money i paid in May was to pay my normal account so they chose to carry on with my account knowing that i requested to cancel it and still debitting my account on a monthly basis which i had to cancel with my bank every month. So i would advise anyone not to open a virgin mobile account.