Issues with MTN

I've been a customer of MTN since around the founding of the company. During all this years I didn't have any problems with MTN until I upgraded my data package online. My payment for March 2023 was R 315 p/m and April's come with an increase of 8%. That was fine except they've added itemized billing which I never asked for and I never had before. In this case R 16.52 + vat. After I've received the new invoice I've tried to cancel itemized billing with MTN champions 3 times, it didn't work. One of the MTN shops tried to help me through downgrading the package but the result was confusing, they couldn't help me because the system displayed "the client can't afford this exercise" !?