Welcome to the forums! I don't have any special knowledge here, but the advise you've been given doesn't sound right to me. Either the problem will be related to your account not being configured to broadcast the public BT Wi-Fi hotspots on hubs connected to it (in which case BT should be able to fix this) or there's a hardware problem with your hub (in which case a new hub would fix this).
If you're keen on getting the public Wi-Fi broadcasting from your router (and I think this is very public-spirited of you!) then my advise would be to get in touch with one of the forum mods and asking them to look into why it's not working for you.