Horrible cst service from GETBUCKS

This company is really pathetic, I had a loan agreement with them and all went well. As usual a four month agreement, the first two debit went of smoothly, I changed banks and informed them of the changes - they could not do the changes I had to go to my bank and request the changes, the debit orders never went of and usual you will receive an sms, I call and give the new banking details they update on their system but still no debit order on my bank account in Dec 2017 I receive a call from their call center stating that I am heavy in arears I ask if they have the correct banking details and it was acknowledged that they do I explain to the gent to take the entire amount and finish the account he acknowledges this and say he will do. I go about my life knowing that account has been sorted only to find that account was never debited, I get listed on a credit bureau for non-payment, I call and get a final statement, I get the funds and pay the account only to be told that there is still an outstanding amount on this account - how is that possible? They refuse to clear my name and update the bureau - what am I to do now