Wireless is easily disrupted by a number of external factors, so a wired test is the best way to pinpoint if the issue is with the wireless connection or your line.
Are any other devices disconnected at the same time and are they wired or wireless?
If an Ethernet connected device is also losing the connection then that suggests a possible line fault and some hub stats would be helpful. If you go to http://192.168.100.1/ to get the VM hub GUI. Don't login but instead click on Router Status which is either a button in the top right of the screen or a text link at the bottom of the screen depending on which hub you have. Click on the Downstream, Upstream and Network Log sections and copy & paste the figures from those screens and post them here, don't worry about the formatting or you can post screen shots if that is easier.
The community can have a look for you and see if anything in the figures looks wrong and advise accordingly. Or you can wait for the VM staff to pick up this thread (can take up to 2 weeks) and run checks on your line.
Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong If my answer solves your problem please mark it as helpful as it may help others My setup: Vivid 200 Optical fibre with Superhub 2 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.