Contract upgraded on false promise

I have a contract (data) with vodacom which ive had for 2 years. Some time in November, i received a call from a guy who said he was calling from vodacom. He told me that he could see from his side that i have a contract that was not upgraded and he wants to offer me exactly the same package for a lesser amount. Initially i was paying R329 and according to him, the instalment would be R159. He then advised me that vodacom will send me an sms to confirm our conversation. I never received an sms and after a couple of days, he phoned me again to find out if i received an sms, i told him no i never received it. He said he"ll check, but i still didnt receive anything and he never phoned me. Today i decided to call vodacom to check if the upgrade was done, and i learnt that it was done, and i was now on open contract instead of Top up and my bill is around R5000. I was also told that the upgrade was done by Eltel, which i was not aware of. I then called Eltel to query this, and the consultant just said he's very sorry, he'll move me to top up but then they cant credit me. I then asked to speak to a manager but was told all the managers are not available. I then called vodacom and asked the team leader there to assist me get hold of Eltel team leader. We were given a run around. The lady from vodacom had to threaten them inorder for us to get someone to assist us. After a long wait on the phone, a lady by the name of Manuku came to the phone, and she told me that she'll listen to the recording and get back to me. She doesnt seem to care much about my query. Im still waiting for her to call me back. Im really upset about this as i WOULD never agree to take an open line and with the fact that i was sold lies. I want this sorted out as i dont have R5000 for data.