Billing Errors and Not willing to help

My contract expired last year November 2015 for a contract amount of R369. I then renewed the contract to a lesser amount of R299 per month and this was last year December 2015. For the past two months, January and February 2016, I have been charged the same contract amount of R369.00. I then enquired at the shop where I renewed the contract, Cresta Shopping Centre, why the amount had not changed. I was told by the consultant she does not know and I must enquire at customer services. She was not willing to help, offer to help and come back to me as the client. Why must it be my problem that I get charged more when I chose a lesser contract. Vodacom seems to be willing to take the money but not prepared to assist clients with queries. For the billing of March, I don't want to be paying R369. That is not what I signed up for. I will take this matter to the consumer council and any other consumer complaints journalist in this country. Fix this!!!