Cannot change number on top up contract

I also need to have a number changed for safety reasons and was told that my Top up package does not accomodate that! M question is if it's not a real contract why are we bound by contractual terms?! Vodacom does not care for the safety of their users and like the other mom who is concerned for her daughters safety we are left with no choice if we cannot affrod the penalties but to leave our children exposed becasue our contracts are not contract enough to allow for a safety change in number!