Zone Fitness Nightmare!!!

sooo some what 6 years ago i had a contract with zone fitness Wynberg but within the seven day period i cancelled....and they gave me back the R100 i had paid... but strangely the debit order came through and i cancelled it now some six years later i get and email from Norman Bissett & Associates saying i owe them R3845.. i have called zone fitness they told me my contract was never cancelled on their system... what kind of business are these people running.... because i have given them the date and date in which i canceled the contract... and they have affected my credit score with this madness