ItsAqua Ok, I really recommend you give the tires another chance. I really suggest that you get a pump that tells you PSI, as low-pressure tires are one of the leading causes of flats on scooters (it will also kill your battery life - most basic bike pumps should work, as long as they have a PSI gauge). As for an extender, these Slime brand valve extenders are one of the best accessories I’ve gotten for my Vsett.
I was also having trouble even getting my tires inflated with the included extender, but I’ve had no issues since I got these. They have a mechanism that allows you to disconnect the pump, without letting any air out… it’s awesome totally recommend it!