Unfair debit over my account

I once had a credit card with nedbank while i was working. I then became unemployed so i couldn't pay the credit card anymore. The credit became prescribed. After i found job i communicated with nedbank to debit R1500 pm but instead they debited R4900 from my account i tried communicating with them they keep on saying they will reverse it. Today as i speak they debited R2600. They do this on a prescribed credit. And on top of that they debit huge amount where i end up not surviving financial. I am still under debt review i don't qualify for any student loans for my kids . Today i didn't ho to work because they took my remaining transport fare