What can I do to avoid being the victim of scam emails and phone calls from anybody who's not from Virgin Media?
Look for the general patterns and format of the information you are receiving and see if it fits with the pattern and format of any of the well-known scams. Some general info on how VM operates also helps e.g. VM do not make outbound tech support calls out of the blue to customers, nor do they ever require remote access to your devices nor do they ever require access to your online banking. If any of those requests are made, then it's a scam call.
In the case of emails, look for the true source of the email. The sender may appear to be VM, but when you look at the actual sending address, it may come from a random Hotmail, GMail or other hacked email account. Poor grammar, punctuation and spelling are often a giveaway that the email is a scam.