Vodacom contract

Good afternoon, my aunt got a call from a consultant from the Vodacom contract department and wanting to offer her 3gig and 100 minutes. My aunt has a contract already where she gets 50 minutes and 5 gig and the payment is R750. The consultant who helped her goes by the name of Ms Moodley . She said it is migration to another 3 gig and 100 minutes. I declined the offer cause already I am paying R750. Then I got a message that on the 15th I have to pay R858 however when I spoke to Ms Moodley I said no. They said I agreed the contract through tobi, yet Ms Moodley called me and we had a conversation through telephone.

Can this issue be resolved immediately.