Cell C cellphone contract

Morning

My cellphone contract expired in June/July 2024, I then cancelled my contract with them on 13 September 2024 where they said I must give them grace period of 30 days which I did, on my debit date which is 25 of every month they debited on 25 September as agreed and gave me data and minutes. On 13 October 2024 my allocated data and minutes disappeared as my contract with them had lapsed, but now they have handed over my account to some collection company. I am gatvol with cell C as I have been their client for the past six (6) years and this is how they thank me