To which I have to add that the exact same thing has just happened to me with this seller, so this looks incompetence or fraud on the part of the seller rather than a simple accident.

I tried to e-mail them about it and the mail bounced, so I raised a claim with PayPal. I have been refunded in full in under eight hours, which must be a record.

This feels a bit unfair to the seller, but, if they've sent the wrong battery to two of us and their e-mail then bounces, well, **** 'em. Guess I'll go after a Polarcell instead...