Terrible Terrible Service from MTN Business with no feedback!

I have 4 Mtn Business telephone numbers with mtn. I always got excellent service BUT I am having the worst service at the moment. One of the phonenumbers - the bill went from last year Sept 2022 with between R700 - R1 200 monthly. No one can give me answers - no one gets back to me - this is a top up contract!!! How can I get ANY FEEDBACK FROM MTN BUSINESS. WOULD NOT RECOMMENT THEM TO ANYONE.