Seriously though, Zojirushi have been around since well before Mr Hinkes achieved any real level of media prominence.
I bought two back in 1998 and they're both still going strong and keeping my drinks hot for hours. I bought a Thermos Ultimate to try too when they got some rave notices on here, but tbh I don't rate it any better than the Zojirushis and I prefer their design.
I'd be surprised if you can't get any. Being very happy with the Kahtoola Microspikes I've had for a few years now I just googled for them and it looks like they now come in 5 different sizes (only 2 or 3 when I bought mine) going all the way up to size 15!
Apparently an unforseen consequence of the ridiculous "Black Friday", no doubt added to a more expected rise in volume ahead of Christmas. If it's affecting Yodel like this then I expect it's affecting other delivery services too.