Sorry I've only just seen your message. I downloaded tbe virgin media app and when I tried to test for a black spot it asked me to scan the bar code on my router to set it up. Because this did not work it said to sign into my account to see if I was eligible for an upgrade. This is where I saw I could have a super hub 3. I've since found out you only get a free wifi booster with certain tv packages. Hope this helps.
Sadly I think we've got a different issue, as we've already got a Hub 3 and I don't think we're due an upgrade. Up until now it's been mostly brilliant (I think we've had it for around 2 years), and it's definitely nice and quick.
Good luck and I hope your replacement unit arrives soon!