Anna -
Thank you for that Hearsay site.
I haven't explored it all, but what I did scan reminded me of the remarkable phraseology in the letter below. Maybe I'll submit it to them as well.

Taken from a Tokyo dunning letter to an American customer:

“Dear Sir:
If you fail to manufacture your ancient payment soonest, we shall take such steps as to cause you the utmost
damned astonishment!
Cordially,
(signed)”