Contract not cancelled since Mrch2018 and still being billed

I am very upset my contract expired on the 07 March 2018. I filled in a form for the cancellation off my contract and emailed my cancelkation on the 5th Feb 2018. As I installed uncapped with Afrihost we are going into May month my account is still being debited with the amnt of R980.18 and my contract is not cancelled. I have phoned the call centre 16 times with reference number and went to branch in clear water mall aswell. When I call the call centre there reply is as "I have send it to the billing departnent and there is nothing I can do" there turn arround time off 21 days has passed Is there any one who can assist to cancel my account and refund my me my money with interest back to my account. If it cant be resolved in 72 hours, please send me a letter of deadlock and will have know other alternative then going to the ombudsman as this is going on since the 05th Feb 2018. I think I enough is enough.

Hope to sort this asap out.

Thank you