Poor sevice

I have a new contract with vodacom wich i have taken out at Randfontein vodashop Tamboti mall. The contract that i have signed for was R1300 for 2 A7 samsung phones. Now all a sudden my account moved to R1966 per month. No one can explain this to me and vodacom does not respond to my emails. Can some-one help me on this matter. I have been with vodacom for a very long time but i see it is time for another network.