I am being harassed to pay for free months

I joined gym company in December, I was told i have 2 free months and no joining fee,and the first debit order was suppsoed to go off on the 25th February. Having said that, my contract also stated that if I wanted to cancel I should do it within 5 days of joining, I went within the 5 days to cancel because i got an offer to work in Lagos end of Feb, Dwyne the consultant asked me not to cancel,that I can continue working out for free he will transfer my contract to someone else before the end of February,which he did. he also drafted a letter for me,however this rude lady who is in the sccounts department keeps on sending me smses every day and is very rude,she even threatened to blacklist me, she says I owe R398 till end of March,and I asked her for what and where is it written? I need an intervention because I think I must also get my lawyers involved.I did not even have an access card for that metter