Having reached the 48% charge club recently I went through the firmware updates and all other problem solving solutions etc that, near as I could tell, didn't work for anyone else either.
I finally made the call to Bose Customer Service. Having explained that I went through every possible solution and detailing that I knew this was a clearly known issue, Bose had no hesitation in organising a replacement set of sleepbuds.
I sent the old set back (case and buds only) on 9th April and had the new set returned today. That may seem like a long time, but there were 3 public holidays in that window, so effectively a 10 working day turnaround from despatch at my post office, to receipt today.
I hadn't realised how much I would miss my sleepbuds so I'm delighted to have a new set ready to go. My ability to get to sleep has been sorely hamprered: I'm looking forward to comparing sleeptracker notes between buds-no buds-then buds again.
As an experiment I'm going to try charging the buds in the case while it's NOT connected to power - and then recharging the case while I am asleep. I recall seeing a case here where that seemed to provide something of a fix.
All in all...if anyone has issues with the 48% charge problem - call support. They will help you! I suspect my case wasn't their first rodeo with this particular problem.
I couldn't care less if support send a replacement etc, thats their job so I'd expect nothing less, and lots of the replacements don't work anyway. When I discussed other options or a refund they wouldn't help. Bose deserve no credit for such a catastrophic failure.