TELKOM SOUTH AFRICA REFUSES TO REMOVE EXTRA AMOUNT ADDED ON MY INVOICE

I took a Contract for a laptop including a pocket router for R453 sometime early last year..all of a sudden when my invoice gets in the installments increases every month from the original amount...this August they are requesting R823 when I asked why they said subscriptions were added to my payment I told them I didn't know anything about them and I can't afford that amount...they haven't helped since I've been calling for the past 2 weeks and tomorrow is the debit day . honestly I'm stressed