This concluded today.
From the beginning... As I couldn't get it to work, I contacted the seller and they referred me to BlackVue UK. They were quite insistent that i must've wired it wrong and I repeated the question - 'this definitely works with the 750S?'; 'YES'.
3 days later I pulled the car apart again and ran it direct from the battery to no avail. I rang them again while I had the car apart and they said it must be the unit. Send it to us for testing; which I did; two days ago.
Today I called them and they said they'd contacted Korea HQ and they said it won't work with the 750S... I'm getting a refund.
Now I'd like hear what you guys would do in this situation. I ordered it 2 weeks ago today and i've had the car apart 3 times trying to get it working - If i'd've put it in a shop they'd've charged me plenty surely.
Just to reiterate:
Seller said it would work
BlackVue UK said it would work
BlackVue Korea said it won't work
It doesn't work says me!