OK, here is the timeline as best I can put it together. Not sure if it will help you, but I would certainly call them and try to get a better resolution. You are spending upwards of $500, I don't know about you, but I work hard for my money. These are essentially toys that fulfill a want, not a need (unless you are a professional pesting person) and I think your hard work should be respected a little better.
AV Booster arrived to me early June '17. First trouble was noted on Aug. 21, '17. It was sent back on Aug. 26, '17 (on their dime) for warranty repairs. I received it back around Sept. 21, '17 and it worked good enough to fill one tank once on Oct 7th, '17. By mid Oct it was no longer working as I attempted to top off the tank. It was sent back for a refund shortly after that. I was very respectful, but I put my foot down and insisted on my demands.
They no longer sell the booster at all. Now the Nomad one is out of the picture too. While I could be wrong, I see a trend, one that I don't like.
Good luck.