Billing Concern

I visited the Mtn store at Clear water Mall on the 20th of June 2015 , to upgrade my existing cell phone and to conclude the contract in my name as it had previously been in my dad's name. The consultant assisting us failed to inform us of the additional charges i would incur by undertaking the upgrade and concluding the contract in my name( which entailed what she explained as a transfer from my dad's account to mine). It therefore came as a huge surprise when i was billed R900 by mtn. The statement i subsequently received contained no breakdown of the charges i had incurred and thus offered no explanations as to why i had been billed that much, when i should have been billed R440 (inclusive of insurance). <br> <br> On the 22nd of July 2015, i visited the mtn store at west-gate shopping centre and was advised that i had been billed R900 because i had incurred an \upgrade charge"and a \""transfer charge\"". How can I be held liable for terms/ charges that i did not expressly consent owing to a lack of knowledge about those charges especially since there was an alternative way of opening the account. """