Unjustified debit order

Subscribed to the new updated router for rain the total cost for the first debit was R650 an month later there is a SMS stating that there is not a increase of Around R3O after one month. this is unacceptable after one month we agreed on the price of R650 is this legal? I understand rate increases etc. but really Rain after one month? I do not agree with an increase so early. what next in December you will increase it again? You sell a product raising the clients expectations then a month later you increase the agreed debit. Please give me feedback. the account is under my Fiancé. check the system per the ID number provided.