charging me although not my error

I have a credit card with African bank at the start of this month I called and told them I need to change my debit date to the last day of the month as well as my banking details. on the 28the I got a sms to say my credit card is blocked due to non payment I called them again and they apologised and said it will go out on the 31 come the 31st no debit goes off so I manually pay the account and guess what when I pay thy take off 200 plus amount as arrears

how is this my fault

reply on email only sort this out