You don't have any kind of warranty. No paperwork = no warranty. You're now relying 100% on SOGA and fit for purpose.
WHERE DID YOU BUY THE CAR FROM? GARAGE FORECOURT, YOUR HOUSE, RANDOM ROAD IN THE MIDDLE OF NOWHERE...?
And stop looking at the pressure, that's not your problem here! It may go up, or it may stay the same, or it may fly off the scale. That could be reading incorrectly, it's the lack of physical oil in your sump that's the issue here.