Demand for payment to Cosmex Inc.
1. The "demand for payment"-letter is addressed to Cosmex, a Company known to the Delavigne Corp. That is why I would not write "To whom it may concern", as the writer - Philip Cheeter - knows pretty well who is the addressee. I would write: "Dear Sirs" instead. "To whom it may concern" is in my opinion only to be used if a wider public is the addressee or if the addressee is not known.
2. In the same story the question was how to conclude the letter. Gymglish recommendation: "I hope we can resolve this issue in a civilized manner". NO ! This wording contains a threat, at least under Swiss and German law. Because it implies that if it can't be resolved in a civilized manner, the Delavigne Corp. might apply uncivilized methods. If "with friendly recommendations" is inappropriate, why not omit any such wording and stick to the "Yours faithfully" ?