I must pay for Data and Minutes that I did not use after the contract was cancelled

I am highly disappointed with the service I have been receiving from Telkom, I cancelled my contract on the 3rd of December with the following References received via Telkom APP ********** 6 / ********** 5 / ********** 1 for my family free me account. But in January I notice that the account was still active I then went to the Telkom APP as I was instructed at the store that I can only cancel the contract on the APP. Then on the 1st of January I cancelled my contract again on and received the following reference numbers ********** 4/ ********** 5/ ********** 5/ ********** 9/ ********** 6 via the Telkom APP. On the 1st February 2019 I checked again and noticed that Telkom has loaded another Data and minutes and I did not use it. I then immediately contacted Telkom and notified them of this and to cancel the contract immediately but instead they told me not to use the data and minutes to follow up with them on Monday the 4th of February 2019. I sent them an email around 13:07 PM and also gave them a call at 14:20 and I was told that my contract was cancelled at 13:20 PM. But Now I received an Invoice stating that I should pay R 1015.10 at the end of February for the data and Minutes I did not even use for the month of February. I called them again to explain this but was told the data and minutes were already loaded for February even though they have cancelled and I still have to pay that amount. Their Manager was unavailable to take my call. Is the Telkom APP that's been used for cancellation a ****??