Bad service Vodacom

I upgraded my contract, I returned the handset because they told me it would be free and when I received the contract I had to pay monthly for the handset. They keep on billing me for the handset that I returned. I tried to communicate with them on the platform provided without success. I am very dissatisfied with Vodacom and would never recommend their service. try and speak to a person, they do not give you that option anymore.