Angry customer

I saw an online advert for a sim card only for R249 per month for 24months. I was interested and contacted vodacom. I received my sim and started paying. This year my premium was increased by R16 which I wasn't happy about and I decided to pay off and cancel this contract. I requested m settlement letter and the figure quoted was way too much for a 2yr contract. I was only then told that my contract is a 30months contract not 24months. I requested my phone record and I was told they listened to it and the consultant clearly indicated that the contract was a 30months and therefore there's nothing they can do. I am very unhappy about this false advertising. Also, I am very unset because according to the quote which was done for me on the system it says 30months but the duration says contract is ending 2025. Even on the settlement quoted it gives a 24months description. I don't know where 30months is coming from. I never agreed to such long term. Can someone please attend to my complain.