Cell C increasing monthly deduction without consent or notification

I have a standing Debit order of R105 on my Cell C contract. Then suddenly for June 2021 they deducted R2974.28 from me. I queried and they could not give me a valid reason. I wanted to close the account immediately but was advised to wait so that the query could be solved. Again they deducted R2974.28 end of July 2021. Then again I queried and they want to offer me a 30% discount on the amount. That sim was not in use, I switched the tablet off completely to see what their excuse will be as to why this drastic deduction. Again no valid reason could be given. I have no where consented to any change in my contract and even requested them to show me any consent given. Till now still nothing from them. So they are merely *****ing my money.