Unfair Blacklisting

<p>SSD has blacklisted me under MTN over a wrongful debit order date that they have decided to put under my profile. </p> <p> </p> <p>I specificaly ally told them that I get paid on the 20th of each month. It was only in December where my salary was paid early (15 December) that I advised them to debit the account. For the past 2 months, they have been debiting my account on the 15th after I specifically told them that there will be insufficient funds. </p> <p>They have now blacklisted me due to their own error. Any advise on how to handle this </p>