According to those customers who bought from me and feedback from my main dealer dealing with BMW, there is
rarely such incidents reported from those who followed our instructions. Maybe a little minority with old batteries and forgetting to Power off the unit when going overseas. But this is the same problem for any car cams owners across any brands due to the current limitation of Power source from Car Battery. Try switching on your headlights and engine off on a old battery & u will know what i meant.
You also say "
according to the guy".
so who's the guy? Any proof for your statement? Any
proof from the guy statement?

Maybe you really had this problem, but judging from your 1.5 year old battery, there will be a high chance of overdraining if your had not power off if not driving the car. Stating that the power saver only cut off at 11.8v and not 12v, have u done any kinds of tests & reports to support your claims? If you really encountered the problem, have you contacted the
official channel to rectify & check the reason of over-draining? Even if the power saver failed, it's impossible for electronics devices to be 100% problem free due to lemon etc, else
what is the purpose & meaning of warranty?
I can also
TYPE the hawker uncle who cooks hokkien mee told me that your nick from HWZ is a stirrer & competitor, or just a unhappy customer trying to defame. So are you?
Im sure you are not, but see where i am coming from?
Typing is cheap without proof & identity.