Sky authorise the new sky hub. This is definitely giving you trouble so 100% get it swapped out. It's giving all kinds of errors on admin pages etc that it shouldn't be doing.
Out of interest if you pull out the ethernet cable between the modem and the router does the smiley face go off? It should do this pretty much instantly.
The openreach modem that's an interesting one. I'm not sure who makes the decision. I would assume the engineer although if it broke eg. kept turning off randomly sky would send an engineer to replace it.
I understand your frustration. The only trouble is that line issues like this are not usually ISP dependant. It's generally a fault somewhere which would just transfer to another ISP if you switched.