Phone 150 and get VM to sort it. They have 30 days to sort it else you have the right to cancel your contract. Look below:
Our minimum download speed guarantee
The actual speed of your service may vary, but for new customers and existing customers who change their broadband services on or after 28th February 2019, we now provide a minimum download speed guarantee to your Virgin Media Hub. This is 50% of the advertised speed for your broadband service on the date you placed your order.
The right to end your contract
If the download speeds to your Virgin Media Hub falls below our minimum download speed guarantee for three consecutive days (continuously or intermittently) and we’re unable to fix the problem within 30 days, you may be able to leave your contract without paying an early disconnection fee. That goes for new customers, or existing customers who change their broadband services on or after 28th February 2019.
So if your on M350 you should be getting at least 175mpbs. My answer - Call VM and if it continues after 30 days leave Virgin!
Thanks for sending that over, actually more of a stable test than expected, if your still awake after midnight towards 1am maybe try another test and see if any improvement, however as mentioned above, Virgin do need to be told about the issue directly and tell them that if the issues isn't fixed within the 30 day period that you will want it disconnecting (if that's a option for you)
If going down the route of given Virgin 30 days to resolve issues then I recommend choosing your test computer and keep a log of daily tests as proof of a consistent problem, maybe create an account on speedtest.net