Not disclosed on upgrade..!

Vodacom contacted me in January and told me that im due for an upgrade and also sent messages that say I'm due for an uograde in January, so like anybody would do, I upgraded and it was all good and well, but then I saw my account was a lot and questioned why it was that much, so they advised me that im still paying for the old devices because it was an early upgrade, but nobone no where ever disclosed this with me, because if it was i would have not upgraded earlier, if thats the case and im still paying for the old devices then i need the two devices airtime as well..?? Vodacom can't trick people in to upgrade and tell them they are due for an upgrade but not tell them they are still going to pay the old devices as well, that unfair towards the customer, because now im going to be short on cash this month because of this..!!!!!