Blacklisting

I was once a member at Gym Company and I skipped 3 months of payment of which its R180 times 3 and when I went to enquire about the money im owing for they said its R5000, and that is really impossible, further more that I was told to reapply with R500...lol this people are sick and beside can I be blacklisted for something of which I don't have, I would admit if it was a cellphone contract.