Openreach own the telephone/broadband infrastructure used by many providers, but not all, and manage all repairs. Openreach's customers are the service providers, rather than the end users.
They provide progress updates to the service providers in relation to faults reported to them. Unfortunately, from posts we've seen here, that's usually limited to "we know there's a fault", to "it's being worked on" and "it's fixed". Sometimes there's an ETA for resolution.
Unssatisfactorily, from a user perspective, if you've reported the fault to Sky, it's a matter of waiting for Openreach to fix it.
It's all regulated by OFCOM.
