Contact ME about upgrade,charging both contracts.

I got called last month by auto page menlyn, letting me know that I can upgrade my contract.<br> I went through to do the upgrade, I received my new phone.<br> When the bill came, it was twice the amount I signed for. I called, they actually answered and told me no I am paying for my old contract as well and someone SHOULD HAVE explained it to me. <br> She then said I have to take it up with head office, which I did. They said I should take it up with the store.<br> <br> ...after calling 9 times in ONE DAY, NO ONE answered the telephone, this happened for 2 days.<br> <br> Then they contacted me about a special the following day, I told them no hear me out I have a complaint, and the person said: \sorry we are extremely slow with complaints