MTN bad customer service

2 Months ago I received a call and the operator explained to me that for R20 more they can give me 80G data on top of what I currently received at that stage which was 5G data and 130 anytime minutes. According to the salesperson everything else will stay the same. I agreed and the package was amended. Now I discovered that I no longer qualify for the 130 anytime minutes as this is not part of the package I'm on and if I would like to change my package I'll have to pay R632.00. Ridiculous. I can't cancel my contract neither can I change it.