V60 B3 12v battery critical charging fault

[ML41]

Morning everybody, new poster here. I'm wondering if anybody has had a similar experience to me and, if so, how things played out.

I have a two month old MY21 V60 B3. In the two months I have had the car, a 12v battery critical charging fault has appeared three times. When the warning message appears it makes the car undriveable - on the most recent occasion it was restricting its speed to 7 mph. The car has so far covered less than 800 miles.

The issue first arose when I had had the car for around two weeks. Volvo Assistance sent an engineer who reset the battery. Around two weeks later the issue arose again, and this time the engineer could not resolve it by resetting the battery so it was taken to the local dealer. When I collected the car from the dealer I thought I'd understood them to say they had performed a software update, but on checking the paperwork there is no mention of that, and it might be that they just reset the battery again. A week and a half later, the issue arose again. The car is back at the local dealer, who are now apparently working with Volvo directly. It has been at the dealer for two days (on this occasion) and I am being told it is likely to be in for at least another two days but probably longer.

Is anybody here aware of similar issues, either with B engines or otherwise?