[DaiPlusPlus]

It is illegal.

(If they don’t accept correspondence from any other media)

Companies in every state in the US have to have a USPS mailing address. It’s a simple matter of sending them a proof-of-delivery letter to their business address registered with their state’s company register to request an end to your business dealings with them.

If they ignore it or claim they didn’t receive it despite USPS attesting it was delivered, then they aren’t monitoring their physical mail address and presumably there’s state penalties for that.

Hmmm! Startup idea: a dotcom website that sends USPS mail to business you hate dealing with to succinctly request service termination and no further contact. Any takers?

[bsanr2]

Presumably the inevitable Aereo-esque lawsuits are what keep people away.

[ianai]

Even forcing that should be illegal.