CREDIT BUREAU DEFAULT

I have an advance account with standard bank, I was in arrears some time earlier this year but my account was not handed over. The 5th of may I contacted standard bank requesting the arrears amount so that I can get my account up to date an amount was debited twice in my standard bank account which would cover the arrears amount, I asked if everything would be back to normal and I would start paying the account as normal via debit order and I was told that would be the case. So I have been getting calls from debt collectors regarding settling my account and arrangements, I keep telling them what happened and all they can tell me is the account was handed over to them and there is nothing that they can do. Lately I have realized that the account is under default on the credit bureau and the debit order is debit as normal on the agreed date, now I'm struggling to get credit and i have medical expenses that I need to pay, even standard bank is declining every attempt of credit I'm trying. please update my profile and credit profile according, please remove my account from the debt collectors, the harassment is really too much. it's really affecting me negatively.