Upgrade, nope Pay both old and new

Ok had two Tablet contracts got upgrade dates waited and upgraded to a laptop and the two 7inc tablets for R99, got a massive bill and upon phoning them they told me I still have to pay off the old contracts, this after I asked the staff if this was an upgrade and if all I am going to pay is the new lowered subscriptions, and they confirmed it to me, If I had known that I was going to pay two contracts I would not have upgraded, so Bottom line is do not trust the staff as they are clueless