We are having the same issue "service unavailable". Have spent the last 4 days over the phone with vodafone and still nobody knows what the problem is.
A little background. We had been using the HG659 modem and never had a stable connection ever since we switched to fibre. So we have upgraded to the new ultra hub modem to resolve this issue. Now we have internet running okay but now we have no TV! We even had vodafone lodge a claim through ultrafast for a faulty decoder. We have had the brand new decoder installed but the exact same issue. This has been the most horrible experience since switching over to fibre. We are paying for a service bundle that we do not even get.
Hopefully you could shed some light on this extremely frustrating situation.