Largely I'm happy with my ISP. Except that somewhere in their core network they have a broken link, which means that 0.01% of the internet is inaccessible to me

Largely I'm happy with my ISP. Except that somewhere in their core network they have a broken link, which means that 0.01% of the internet is inaccessible to me, as of a couple of weeks ago when they "upgraded" my connection. Unfortunately that 0.01% includes my friend's computer which runs my backup email servers. Tried explaining this on the phone to the ISP. The script the phone-jockey had basically took me through rebooting the router, trying a couple of different browsers, and then saying that they were pleased to have solved the problem.