Contract Cancelled and I am still being billed

I can cancelled my contract in February and its now April and Vodacom sends me an email saying that I owe R218.49. I called Vodacom to enquire about this and after being transferred to 4 difference people, they tell me that they are unable to assist me further due to not being able to assist me because Vodacom moved to a new system (3D) and they are unable to view all my details. The agent transferred me to the 3D system department and no one answered. I was on the call for 38 minutes and then I dropped the call.<br> <br> Someone from Vodacom needs to contact me urgently. Why am I still receiving invoices when my contract was cancelled in February, I called Vodacom a couple days after I cancelled the contract to confirm that that the cancellation went through and they informed me that it was cancelled and as of the 1st March 2016 I would be on prepaid. They also informed me that the only time I would be sent an invoice was if I went over my contract call limit. I did not exceed my contract call limit and I am still receiving invoices for payment. Could someone please contact me urgently to explain.