Poor service and harassments

I contacted Cell C in August 2022 to advise that I have changed Banks and requested that they debit on the new account. To my surprise they would not debit on the date I requested but debit as and when they please. Also they failed to move my data contract and I got the shock of my life when I found out the account had been handed over. I do not want to be contacted by Shapiro as I ensure I afford my debts. I need this rectified immediately and for Shapiro to stop calling me. Check who did not do their job correctly and fix this mess as it is messing up with my credit score and I am in a process of buying a house. I need feedback ASAP.