Asking your congressperson to look into this actually might not be as futile as some might think. Every representative has at least one office that is physically located in their home district; the staff in these "District Offices" are almost entirely devoted to what is euphemistically called "Constituent Service" (i.e., helping ordinary citizens deal with the Federal bureaucracy, in the hopes that said citizens will reward the representatives with their votes come re-election time).

You might try sending a concise and compelling letter to the representative's District Office address, making sure you identify yourself as a constituent. If you make a reasonable case, then it's quite conceivable that your representative might ask DHS for an explanation as to what happened. And when a federal agency gets one of these "Congressional Inquiries", it definitely gets their attention.

Bottom line: focus your efforts on your own congressperson. You'll probably never get an actual confession from TSA, but you might just force some very senior managers to look into the issue.