Bad service delivery

Blue label blacklisted me for arrears in May. On the 9th of June I settle the account. I had to call them numerous times to send me a paid up letter up to today no luck End of June they didn't update the credit bureaus and it still state in arrears. I have spoken to many of their agents promising me they will sort it out with ni luck. Nothing has been send to credit bureaus and my credit score have been severely affected by this.