MTN, I am very disappointed!

I have been a loyal customer of MTN for more than 20 years. Recently, they have been calling after me non stop for an upgrade. I waited because I was still satisfied with my device and actually just wanted a data sim package. I finally upgraded, after they called me once again. I confirmed with the guy on the other line that I would only be paying the pro rata amount owed, to which he confirmed the amount that I would be paying going forward. To my shock, they debited a much higher amount that I budgeted for a month later. When I enquired, they told me that I still owed money on the device because it was an early upgrade. These things should be discussed with you before you upgrade. I have never had this problem in all the years I have been with MTN. When asking whether I can perhaps make an arrangement, I was told that it is not possible. I did not plan for this and I am so NOT happy at this stage.