Bad service

Good day, my loan account was debited twice and i was promised a refund 3 days ago. I find this unacceptable! I informed the call centre to debit my cheque account on the last day of the month. First payment was done incorrectly, called again to rectify mistake then only to find out that my new loan account was with Collections! I was promised that the problem has been recitified and that my account was no longer at collection but yet again my account gets debited twice (call *** Annie). I'm upset because this has now dropped my credit score and when I app**** for an overdraft this was the reason it was declined. I need this matter to rectified, my money to be refunded and my credit score to be fixed.