Very angry

Had a bad experience with their call centre,I had a contract with them which ended last year and to my suprice when I wanted to apply for the new one I was told I'm blacklisted and when I check my credit report it was them it showed I had arrears which I paid the amount when I call them they told me it was R70 of unpaid debit order of which I know nothing about and no one told about it, I called again to try to speak to the team leader I eas made to hold 54 minutes till I drop the call, I called again yesterday asking to speak to the team leader again and told the agent that I was made to hold for 54 minutes he must make sure the team leader answer my call and guess what u was transfered to the wrong department, I never got to speak to the team leader.