Lies and false information

So when it comes to our Vodacom contracts, my mother entrusts me to decide which deals to go for. She receives a call - the associate tells her about a deal Vodacom is offering us. My mother proceeds to tell her to contact me, her daughter. The associate contracts me and tell me that Vodacom is offering us a data deal at a reduced price. Questions that I explicitly remember asking her are: 1. It is a new contract - she says no and explains that it won't affect our existing contracts. 2. I ask her so is our existing contract prices going to be reduced - she says yes. 3. I ask her how much are we going to pay now - she says she can't give me the exact amounts the system won't allow her to at this stage. 4. She refers to sim cards that are going to be delivered. I say to her but we don't need another sim card - she proceeds to say we don't have to worry about the sim card it can just stay there. 5. I ask her to email me the new prices - she says she will. I then phone my mother to say ok she can accept the offer. So the associate phones her back and seals the deal. It turns out that it is a new contract she was selling us. Now I am trying to get this issue resolved. Vodacom now says that the deal was offered by Mondi Mobile, not Vodacom!! Mondi Mobile's QA department says the associate did say that it was a new contract. After months of back and forth - I have now realised that the associate told me one thing and told my mother the "real" story knowing that the calls are recorded. Now I'm trying to get Vodacom or Mondi Mobile to listen in on the call the associate made to me. I am the one constantly trying to resolve this issue and all Vodacom says is this was done through Mondi Mobile and all Mondi Mobile is a saying is that the associate gave the correct information. The associate told me one thing and my mother another thing to cover her behind. I was on the phone again to Vodacom and Mondi Mobile earlier but no sense of any urgency or wanting to resolve the issue.