Letter of demand for 4 days late!

I recieved a letter of demand on the 4 July because I did not pay on the 30 June 2024 I paid on the 4 July 2024. My question is according to the NCA section 129 I am supposed to recieve a letter of demand 20 busin6days after my initial payment. I did not choose to pay on the 4 July my app was blocked so Iwas trying to sort the app. My question is why did fnb not follow protocol. I'm in the process of switching my home loan, I will not tolerate this!