Prolonging of contract

So I had a 24 months contract with Zone fitness been paying all along then on the 23 month they decided to only deduct R100 which was not an authorized amount because I agreed to R199 monthly, they decided not to debit at all, me on the other side assuming my contract has expired but has now been advised I owe R597 because during lockdown they decided not to debit their R199 and my contract expired in July I am very disappointed. Selina Mo***end from the Lenasia advise unfortunately there is nothing I can do...