Health Avenue gym and their attorney are dogy

Back in 2010, I was working as an intern,I joined Health Avenue health club in King William's Town, for a 12 month contract. But when I went back to school full-time in 2011, 6 months in to the contract, I couldn't afford to pay the gym and I did communicate with them, and I was told that I can not cancel the contract, its either I pay the remaining amount for the 6 months at once or pay installments till I finish the remaining 6 months. Still I couldn't afford.

Late 2012, I think it was around September, I received a call from my mom saying that I have been garnished by Health Avenue. I did a follow up, and I paid the money with their atterneys. I want to buy a house, and I have been checking my credit score and I noticed that my score is low. When I amde enquiries about it, the Health Avenue thing still appears on my credit profile even if the money was fully paid. A few months ago, I made enquiries with their atteneys and I was told that I need to pay R900 to have my name removed from the credit bureau. Why? I paid the money in full, now I have to pay them to have my name removed from the credit bureau?