Unauthorized increased contract

Last year I received a call from one of Vodacom's representatives advising me that my current price plan will be discontinued so I will have to migrate. She further said "Because you don't use all your benefits we have decided to decrease your payment from R365 to R302". I then confirmed with this agent if that includes my insurance with Vodacom she said yes my total now will be R308. Fine I let her proceed. Now I check my balance I see that my total went from R365 a month to R502 a month!!!. When I clicked and checked the details this R308 is only for a line rental and does not include my insurance. I called yesterday and the lady created a ticket to rectify and put me back to a price plan that is equal to what I was paying. Today I got a message declining that because of my credit record?? Does that make sense?? Increasing someone's contract with the same breath refuse to rectify it because of a credit record?? My contract with Vodacom was me paying R365 for 36 months and thats what I am prepared to pay and will pay. This is ridiculous and unacceptable. Day light *******. RECTIFY THIS!!