Vodacom Contract Cancellation

Hi, I'm extremely disappointed and infuriated with Vodacom. After 17 years of being a loyal and paying Vodacom contract customer, I decided not to upgrade my contract and cancel due to financial commitments. My contract was ending in December 2019, and I called in on 10 December 2019 to cancel the contract. The lady that I spoke to tried to sell me another sim only contract and I refused it and explained that I just want to cancel. During our call the line cut of 2 or so times and the lady called me back from Vodacom, I have proof of my call log. I paid all that was due to Vodacom for the month of December. Today being 3 Jan 2020, I noticed that Vodacom has loaded airtime minutes and data, meaning that the contract was not cancelled. I called in immediately and I was told that the contract was never cancelled and I never requested it to be cancelled. I was told that according to Vodacom records, the last time I called was in October 2019, and they don't have any record of me calling in December. I was told that they would only load request to cancel today and I will still be liable to pay for the month of January 2020. This is totally unacceptable as I have proof that I called Vodacom and in fact Vodacom called me after the call cut off. They are claiming that they don't have that on their records. I have asked Vodacom to reverse that data and minutes that they have loaded and they say they are unable to do that. I have no intention of paying for the month of January as I cannot afford it, hence I cancelled the contract in December. I want Vodacom to sort this mess out... Please help me