I assume your PC has BT capability? Can you pair it with the PC? If you can pair it but do nothing with it, I would suggest it needs drivers.
With other logitech devices (steering wheels) I downloaded the similar device drivers from their website and it got them up and running on my PC. Maybe they do a BT headset for the PC? If not do some digging around and find out who actually makes the headset and find their drivers or just try some random ones until you get it running.
When you do... write up a how to for others