DUPLICATED CELL NUMBER AND BAD SERVICE

I have just contacted vodacoms customer care and the agent that helped me was rude and dropped the phone. My complaint is that i bought my phone and sim card at the end of january 2016 from CNA. They gave me a new number as this was a new sim card. However i am receiving a lot of calls and smses for another lady and when i told the agent this she was not helpful and told me that i am using a second hand phone and second hand sim card. This is not true as i have the slip with my new cell number on it. There is even a sms confirming my cell number which is supposed to be the new one which was purchased in january at the bank. now myself and this other lady (details which is with me) are using the same number and all my personal information is at her fingertips. I am dissatisfied with the service i received and there is no solution. Now i must change my number again as the agent at vodacom is unhelpful, doesnt know how to help me - obviously as she dropped the phone and i would like what is going to happen now???