Yep - it's the Epley Manoeuvre that you're thinking of. It's a carefully choreographed sequence of gentle head and neck movements.
Beware that after doing it/having it done, you need to remain vertical (i.e. sitting upright or standing) for 48 hours, otherwise the "bits" that the action is designed to reposition, settle back where they were and you're back to Square One. That means sleeping sitting upright for a couple of nights.
I had this done for me by my GP and an ENT consultant, both of whom ommitted to mention that. Sadly it didn't work for me even when followed up correctly, but I understand that many people with BPV liken it to using an "Off" switch.
It's non-invasive and minimally inconvenient compared to the effects of the BPV, so I'd certainly recommend giving it a try.