Snail mail can be a hassle, but on the flip side, with snail mail, you can send in the request via certified mail with a requested return receipt. This creates a legal record of when they received your request. Thus, if they don't act on it in a timely fashion, you can prove it. It is only tangentially related, but in Patio11's article on handling bogus entries on one's credit report[1], there's this wonderful line: 'I was sending “certified mail, return receipt requested”, which is Dangerous Professional for “Do you like paper trails? I like paper trails. I particularly like paper trails where the United States Federal Government attests to the exact minute your firm learned the contents of this letter.”' While not quite the same situation, I suspect such admissible-in-court-as-evidence[2] traceability of communication is of equal use here.

1. https://www.kalzumeus.com/2017/09/09/identity-theft-credit-r...

2. This is my intuition talking here -- I am not a lawyer. If you have legal questions, talk to one. But, IMO it would be utterly bizarre if USPS record of when a specific piece of mail was received were not admissible as proof of claiming that company got your request.