Debit dispute with Cell c

I had 2 contracts which the 1 ended, so I was on month to month basis, I called Cell c to cancel my contract on 2 Dec 2021 which they did, I received an sms on 3 Dec 2021 to confirm. After the sms my data on the phone was also gone. 31 Dec 2021 a debit of R601.02 was made from and again on 31 Jan 2022 another R619.50. My previous debits was R427.99. The consultant could not explain properly why this amounts was debited. I asked the consultant to open a case with case nr: ***