S.F.,
You have some good points.
However, I take issue with your approach.
To send a letter to an employer based on what you describe.... "appeared that one or both of these young men worked for Cinmgular " is a giant leap of faith on your part.
You should have gotten names from name tags or at least provided the intended reader a description of the young men, a date and time frame for research purposes.
In retrospect I think your letter as written should have been addressed to Mall Management for their followup and handling.
If you hear back please let us know.
BillR.