Terrible service as usual

To my disappointment once again, Vodacom has failed me. I’m so tired of having to go around in circles, no one getting back to me and people giving me wrong information. My contract ended the 21st June. I called on the 21st May to cancel the contract, the lady informed me that I need to ensure the airtime is used before the 30th June as it would expire. She said the 1st June would be my last payment. I confirmed again with her and she agreed. On the 3rd of June once the payment went through. Me having trust issues as I’ve went through this where Vodacom does not cancel your contract. I called up and asked the lady was the cancellation put through she agreed. I then asked her to please confirm that the payment that went off was the last payment that I will receive and she confirmed yes. To my surprise on the 10th June I received an invoice. I called on the 14th and the lady said she would escalate it. I have still not heard anything and I’m absolutely appalled by this service that I’ve been given. The sad thing is my work contract came to an end so am I unable to afford this last payment. Had I been told in the beginning I would have set aside this money. Please rectify this situation as I am now fed up of Vodacom misleading me