I’m tired of these ********!!!!!

I’m tired of these people, I received a call telling me that MTN is stopping the plan I was in and that I needed to migrate to a plan equivalent. The old plan was offering 50m, 500mb,50 SMS, the one one it’s 100m, 1gb. Fine! I asked this guy that called if there’s no cost to this thing and he assured me that there were no costs. Last month, my bill came, it was R1000 more!😑. I called MTN and they told me about migration fees what what and I told them I wasn’t told about this and that they must cancel all of it, I even went to the store at Campus Square and they couldn’t help me. I called and called, now the bill is something else. I’m not paying this, and MTN must fix it