This had already gone past the first level “customer service” level to the 2nd level “technical support” team who sat on it for a couple of weeks, they’ve apparently now escalated it again and they’re waiting for their “network team” to take a look at it.
I’ve basically lost all hope with them at this point.
I’m in the UK, we have a system for switching ISPs that is apparently relatively painless so I’ve started that process but it’s apparently going to be another 2 weeks before the switch can happen :(