What proof could you possibly have anyway? I can’t imagine that they’d discount your experience if you didn’t have a surreptitiously filmed cell phone video or something. Give it a try instead of throwing your hands up in despair, lol.
If one possibility is that you get a truly horrible score back and you do nothing about it, and the other possibility is that you call and your scores get delayed while they figure out what happened, I’d take the latter in a heartbeat.
The SAT page linked in the post I linked says this about complaining about testing conditions:
If you have a complaint about the test center or testing conditions, send us a letter explaining your complaint. Your scores could be delayed while your complaint is investigated.
Fax: (609) 771-7710
Email: testcenter@info.collegeboard.org
and you have the address already.
Email would certainly be fast. Customer Service would also, without the added anxiety of wondering if someone has looked at your email yet.