I am being charged for an account that has been paid off and closed.

I paid off and closed my revolving Loan account with standard bank fourways mall in March 2022, to my suprise 2 months later i got an email saying i have overdue payment pending, i have tried to reach standard bank to resolve the issue but no one seems to know what they are doing or can help, this account been closed and paid off - how come am i still being charged for an account that is paid off.