Montly Subscription that I am not aware of

I have a contract with Telkom for which I should pay R250 monthly , since August Telkom has increased my amount to R350 Monthly , I realized this after monthly installment was missed to check why is my bill so much and why was it increased without my knowledge I was told by an agent that Telkom has inserted subscription on my account, then the problem will be sorted then i will be informed about the changes, I received invoice for October Telkom has inserted other subscriptions with out sorting out the problem, I am so disappointed with Telkom they don't take their clients very seriously