Nedbank day ******* in accounts

MDS M/C R8.60

I want to know why an account that’s clearly overdrawn, keep getting debits of R8.60 about 5 to 6 times in one day everyday, does it make sense that a person has to be overdrawn so much that by the time you put money in the account there’s nothing left because nedbank is *****ing money daily from a person’s account without clarification, what is being debited so much in oneday? Doesn’t make sense and it keeps getting worse, at this point it’s almost at R400.