CONTRACT/NEW CONTRACT/DATA USAGE

I am a customer of vodacom for 15 years. I am on a contract talk 100 for the last 24 months. The TALK 100 does not excist and i upgrade to a new contract. The TALK 100 contract still excist untill end of February 2015. My new contract start in 1 March 2015. Vodacom give me a new phone which i have now for eight days. I rceived a sms from vodacom that my dta usage is R3814 and they gave me a telephone number to phone. After 10 min this ammount went up to R4000. I have spoken to the customer care and asked Michael Mililo who is the team leader and he did not phone me back at all. I phoned the Bundle people and talk to Neoil Boya and he said i must phone accounts department. So i phoned the accounts department and they say they can't help me. So i phoned Vodacom head office *** and ask for the CEO and the switchboard said they will phone me back. Still no phonecall received from anybody. They charged me R4000 while i have a contract that said they are not suppose to charge me for this only when the new contract started. How can vodacom breach the contract?Vodacom tells me i use this data 12h00 night and 4 in the mornings. I never used my phone that time in 15 years!