Telkom cancellation and debit issues

Why am i required to cancel my month contract after the 24 months have passed. On top of that im getting errors on the website that they cannot retrieve my information when I'm trying to cancel. Upon calling the customer care im being told that my account was in collection, this does not make any sense to me why it was in collection because I had money in my account on the debit date, but it was not debited.