I’ve had mine or just over a week and had it out for just over 100 miles of riding over 6 days. I weigh 175 and am riding on slightly hilly terrain, most of it paved but some of it gravel. I’m riding at pedal assist 2 and 3 with light but consistent pedaling. My speeds are 12mph and 16mph respective to those pedal assist modes. My rides have been varied from 13 miles to 22 miles and I’m seeing about what they advertise for range. Which is to say, my longer ride of 22 miles left me with just over 50% charge. Two 13 mile rides over two days, no charge between the rides left me at 50% at 26 miles. Also, I’ve done a bit of pedal assist 4 and throttle only mixed in.
Extrapolating from that were I to ride at throttle only I’d expect to get about 25 miles on a charge. And were I to attempt a 45 to 50 mile ride with peddle assist I think I’d have no problem getting that before losing my battery.
One last thing, I’ve got a couple of semi-steep hills on my gravel road and have had no problem. I’ve taken it up some steeper, longer hills on pavement and shifting down to the 1st or 2nd gear I easily made the top of those hills at about 13mph in peddle assist 2.
Based on their site and reviews I’m really happy with the performance and feel it’s very much in line with their stated specs. All that to say it seems clear that your bike is not operating normally and should be covered by warranty.
Hope you get it resolved because when the bike is functioning as it should it’s a blast to ride!