Quick update: PSWPower/"Alice" has behaved extremely well, and I'd like to say so publicly. I was asked to send various photos of multimeter readings for the battery, charger and fuse, which I did - seemed a very reasonable request to me. No comebacks from them - just a request to send the battery to Germany for repair. As it turned out, I couldn't because of all the tight shipping regulations regarding Lithium batteries, especially faulty ones. No argument from PSWPower about this, and they offered to send me a new battery and charger. We quickly agreed that I would pay the shipping costs for this, because I would have paid shipping costs to get the duff battery to them, if I that had have been allowed. Seemed entirely reasonable to me.
No problem with communications between myself and Alice - she replied to all of my emails within 24 hours and at no point came across as difficult or evasive. Just sayin'...