Non Payor!!!

I always send an invoice and then if not pay by 5th days, I will send a reminder and then on the 7th day, I will start the non pay dispute.  I did get one reply for one but what I don't understand if there is a problem, why doesn't buyer communicate before you do the dispute.  here what it say, do you believe or not.  It is so hard know what to do, are they trying to get sympathy in story that may be not true or it could be really true. Here it is

"Hi...I am very sorry that I have not paid. I am afraid that sometime this week, I had an envelope
with over $300 vanished.  My daughter is paralyzed from the neck down and I am afriad it might have
been one of her nurses.  Can you please extend me grace and allow me to not pay for this?  If it is
a major problem, I can pay for it on Monday.  Thank you."