Hmmmm...

"...the main battery failed,..."

Like you, I would assume, at least at first, that "the main battery" would mean the hybrid battery, now I'm not so certain. The only thing left that would lead me to think that "the main battery" means the hybrid battery is that I would think it would not take a week to get a replacement 12 volt accessory battery.

But then again....

Did the DC-DC downconverter fail and that resulted in the failure of the 12 volt accessory battery?

Is the 12 volt accessory battery somehow special or unique?

Or is it taking a week to get the down-converter AND a new 12 volt accessory battery "package"?