Vodacom mislead me

They are not even worth 1star. A lady phoned me from Vodacom claiming that I'm being overcharged for my 2 phones that I have on contract. She said she'll migrate me to another plan but this was not an upgrade. I asked her if the price plan will change and she said no. Got the shock of my life when I received my statement for the month of December, its more with R500 than what I normally pay. Basically I was mislead and sold something under false presence.