Bad service --- Contractually Paying for 2 Contracts

My name is Ogeshini Moodley I was recently allowed an upgrade, after visiting the Clearwater Mall Vodacom store I asked the consultant who said yes i can downgrade from a contract that i currently pay R1389. A smart top up plus, so i decided that night to go online and selected a contract which i got confirmation of my new contract. i received the phone about 10 days later which was just last week. this week i checked my bill only to find out that i am going to be charged for the old contract handset and the new one!!! so i am told that i have the pay the same amount that i was paying even though i have been given a new downgraded contract this is totally unexceptable!!!