Reward co & MTN customer service is not looking after customers

Reward Co phoned me and missed informed me about a contract that is cheaper and better than the one that I have for more than 20 years. They confirmed that I will only pay R350 and not the R450 per month because I am a VIP client and my Iphone is paid up on the contract. I beleived them and received the first account for R1 077 I went today 19 Feb 2021 to MTN in Menlyn. Spend an hour there and had to phone 135 and after 30 min I was informed that Reward co have to cancell the contract. I have to wait for 24 hours or phone them. I feel my contract and account is with MTN but they cannot help me. Why is Reward co lying but MTN who bills me cannot help a client that is with them for more than 20 years