cell c unexplained debit

I settled and cancelled my cell c account in February 13 2019, in 20 April 2019 i have noticed a debit on my account of R 409 and when i asked why my account was debited i was referred to retention department and was promised to be called which never happened, all the time i was to call them back and they keep on keeping me on hold and at times i would be on the phone with them for more 25 minutes, and now i am told that R 276 and that the deference which no one knows how much is suspected or suppose to be for the March month benefits which i did not get. so all i want is the R 409 to be paid back to may bank account or get clear explanation is to why i am not going to get the full amount.