You need to use the Connect app to perform the Home Scan in the area where the signal is low(est), see the screen shot.
Info below from https://www.virginmedia.com/help/booster-and-wi-fi-pods
Yes, but only if you’re not getting download speeds of at least 20Mbps in every room.
Our home scan feature will guide you from room to room to carry out WiFi speed tests. If it finds a potential signal-less spot, it’ll test our broadband speed to the WiFi Hub to make sure there isn’t a problem with your network. If everything’s okay with the Hub, the app will take you through to order a WiFi Pod to help boost your WiFi connection.
You can also call 150 from a VM landline or mobile, or 0345 454 1111 from any other phone to order a pod (they will only send out one at a time, and there must be an interval of at least one week before a second order will be accepted)
Call around 8am if possible when lines first open and are least busy.
They are free since you say you are on a Volt package.