Kloof, can we step back a bit please, is your problem that you have a desktop PC which you wish to connect to your new Virgin router without a cable and the desktop PC is not wireless enabled? Is the router in the same room as the PC or at least fairly close and not through any mediaeval thick stone walls, if so then any USB Wifi dongle from Amazon such as
Amazon.co.uk User Recommendation (this isn't a reccomendation as I've never used one just an example) should do as long as you have a spare USB port. Your engineer doesn't sound as if he was very helpfull, ours have always been really good.