Contract amount changed without notice

I have a contract with Telkom Mobile that i pay R99.00pm (Debit order goes off my account every month). The contact has been active since January last year(2014).<br> <br> Now all of a sudden they debited R190.00 from my account since November and December. I e-mailed Marietjie de Beer at Telkom mobile about this and she said she does not know then referred me to the call centre. <br> Called them and a lady by the name of Chante Smith picked up. I asked her why am i now charged R190.00 instead of R99.00, she said something was added to the contract. I then asked why was i not informed and she does not know.