What is going on MTN!

What is up with MTN's billing? I have been a loyal MTN subscriber for over 20 years. We have been doing an EFT payment for the last 10 to 15 years, after MTN messed up my debit order while moving between billing packages. I have always tried paying after my salary is paid, normally after the 25 to 27th, depending on my employer. Since December 2020, MTN is demanding payment on or before the 19th of the month. I fail to find the communication regarding this change. I have spoken to 135 and confirmed that I am not behind. What is going on MTN?