unauthorised interest charged

I called Getbucks to get the settlement amount of my loan and their banking details so that I could transfer the money and close the account. The consultant I spoke to said she could not give me the banking details instead she was going to load a debit order on my account and the settlement amount would go off my account within the 2 days that followed. 2 months down the line there is still an amount owing because the debit order was loaded to go off 3 - 4 weeks later. Her mistake has resulted in me incurring interest charges. I called Getbucks and spoke to another lady called Mpho, she promised to call me back to give me feedback , a couple of hours later she still hasn't called, using my airtime I called again only to be told she has knocked off and now I have been told I need call another number.