new-b, the way you are describing this, it sounds like the switch is functioning correctly. Forgive me if I'm repeating myself, but I want to make sure that you realize that when the light is on any of the 3 main levels (low, med, or hi), that it can change between 2 SUB LEVELS by double clicking.
Say you've got it on the medium level, double clicking will alternate between Medium 1 (65 lumens) and Medium 2 (21 lumens). So, if you keep keep double clicking it will go back and forth between 65 lumens and 21 lumens, and when you decide which of those you want for the medium level, you simply turn off the light (single click), and the light will memorize that as it's medium level (either 65 or 21 lumens).
Then, when you cycle through the 3 main levels by holding down the button, the sub level you just memorized will show up as the Medium level.
Same thing with the low level. First, do this in a dark room, maybe a closet. When you are cycling through the 3 main levels (holding the button down) , stop when the light is at the lowest of those 3 levels (let off the button), but leave the light on. At this point it should be either 2.8 lumens or.1 lumen.
Now, double click and light should change to the other sub level, then double click again and it will go back, alternating between 2.8 lumens and .1 lumen each time you double click. When you've decided on the sub level you like, turn the light off (single click), and it will memorize that sub level as the low level, and now when you cycle through the 3 main levels it will use that newly memorized sub level as the Low.
And of course you use the same procedure with the high, but with an added twist that we won't discuss now.
I just want to BE SURE that before you send your light in for repair that this simply isn't a matter of understanding the UI. I'm not meaning to insult your intelligence, just wanting to clarify the situation, as this type of UI can be perplexing at first.