I am Black listed but already fully paid on my loan on time. Any advise?

Hello members any advise for removal of name in black list. My story started when I applied a personal loan in Robinsons Bank last july 2012 50k for 2 years via Salary deduction. I resigned from my company last Feb 2013 and I was not able to pay the monthly until March 2014 and decided to pay all the balances. So I am fully paid before the 2 year payment which ended july 2014. I have been applying loans from other banks after that but they keep on declining it. Until I found out that the reason was that my name is under the black list. I called Robinsons Bank and they said that the reason why they sent my name in the black list is because I was not able to pay the monthly dues after I resigned. They also said that they cannot retract my name anymore from the black list. Any advise?