Incorrect billing

On the 25th of September 2015 my brother and I done a change of ownership of his Samsung Galaxy Note 4 Telkom contract to my name and now on 10th of October 2015 I received an sms from Telkom stating that my bank account will be debited for an amount of R578.20 on the 15th of October 2015. I went to my local Telkom branch and they stated that my information was captured incorrectly that's why I've received the sms that my account will be debited and they also informed me that nothing can be done about it and if I don't pay by the 15th I will be charged interest until I do. When I signed the contract I distinctly indicated that I would like to be debited on the 25th of every month so in essence I am being charged for a mistake that was made by the Telkom employee that captured the information incorrectly. Another thing is that I am being charged an additional R79.20 pro-rata when I am only supposed to pay R499 as per the contract. I would like clarification on this matter and for the billing issue to be resolved as I am not willing to pay interest for a fault that is not mine nor am I willing to pay R79.20 pro-rata which I was never informed of when doing the change of ownership.