Cancellation of contract

My vodacom contract was about to expire and was due for an upgrade. I called Vodacom and asked them to cancel my contract completely, i want to go prepaid and do not wish to upgrade, the lady told me that it is better to just downgrade so that when i want to get a new contract again, there wont be any problems applying again, she then offered me a R99 contract, which i said send me the details first before i agree. I did not receive anything from her and then phoned again, talking to someone else, who could not find anything on the system, she then said that they cant offer us a R99 contract, but she will send us another offer after discussing it with her supervisor. We received an email with a quotation of a data contract which i do not need and i phoned them again, while holding on the recorder said that my contract was due to expire on 2023 meaning that they already put the new contract in place without my consent. The lady that spoke to me then said that i will have to pay penalty fees if i cancel this contract and that i should speak to another department that said they will escalate my enquiry!! Please help me as i can not afford this contract and wanted to cancel it in the first place!