I take no position on the claims, but the correspondence was interesting.
One notices the sarcasm "this letter was received at x, i.e. long after office hours had closed" yet no doubt if the item was delayed until 8am the next day they'd still whinge.
And the first documentary which they claimed they'd sue over apparently didn't go forth to "legal" according to the production company despite the bluster, so has any legal proceedings been filed this time, despite the bluster and threats.
Talking to my solicitors, taking legal advice or even getting a nastygram is a lot more than actually filing a claim. I guess they didn't file nor get an injunction to stop transmission either, else we'd have heard about it. Odd, as if I was such a big player and being so clearly defamed, would I wait until transmission had happened.... not on your nelly.