Unhappy Customer

Last year I took a contract out for a laptop with Altech Autopage where the agreement was or the package deal was I pay R289pm and get 2GB data during the day and 3GB data midnight. In January my father went too change my package deal too a 2GB top up without any consent from me (I am the account holder). Since when does Altech Autopage change package deals without the consent of the account holder, is that not breach of contract? And does that mean any person or relative can go to Altech Autopage and act on behalf of the account holder and change package deals as they please and Altech Autopage just happily do the changes without permission from the account holder? And since I've signed up for the contract I've been having internet connection problems until now which makes its very frustrating because its almost impossible too use the internet.