CHARGED MORE THAN WHAT WAS AGREED ON THE CONTRACT BY TELKOM

I was called by Mondo Company, which is promoting Telkom Products, during the telephone conversation i agreed to take a contract of Mobile Router which i will pay once off admin (which was deducted on the 13th July 2018) and on Monthly basis i will pay R179, it was on the 10th July 2018, i even asked the consultant if there are hidden costs and she said no, the amount that i will be paying is R179 only per month, my router was activated on the 19th July 2018, to my surprise when they sent statement on the 1st August 2018, the amount due was R333.48 meaning from 19th July 2018 the day that my account was activated until 1st August 2018 they charged me that amount, of which it was not what was explained to me, and our agreement was they will debit on 15th of every month, which was suppose to start on 15th August 2018. I called them to enquire about this matter, they told me they will do investigation and will come back to me, they didn't come back to me, i did a follow up call i was told the investigation is still in process they will come back to me, they never did, i called again on the 3rd September 2018 to check how far, the respond was the investigation feedback didnt come in my favour, i was told about the extra amount that was charged, of which is not true. I'm afraid now because they will deduct what was not agreed to on the 15th of September 2018, which is R333.48 plus R179, they didn't deduct R333.48 in August because of the investigation, please help me...