Got the same issue did you get a new telephone adaptor in the box or did you use the one you had with the Hub 3? Apparently you should be using the adaptor within the Hub 4 box however this wasn't included!
Thank you for your post and welcome to the forums.
I apologise that your first experience over here isn't a good one and also for the issue you're faced with. Upon checking your account I have booked a technician to come out to you at the earliest possible time. If this is not ideal for you or inconvenient you would be able to re-schedule this through your online account 🙂
Hope this helps.
Ryan_N - Forum Team - https://community.virginmedia.com/t5/custom/page/page-id/WelcomeGoodFolk