No Answer-Credit Control

I called into the MTN call centre 01/03/2024 to update my banking details due to closure of my old account. I double checked on the 18 March 2024 and was advised that I cant change my banking details due to the credit limit on my account being zero?? Was given the number *** to contact their credit control, which never answers how do I sort this as now if no payment is received my account will be suspended.