[stumped]

I gifted a couple of kobo readers at xmas

for that, i created a couple of disposable gmail accounts, in case I deecided to pass those on also ( but I didn't )

yesterday i got a purchase receipt from kobo for a £4.99 best sellet, on one of those accounts. payment details when I login show last 4 digits of a visa card - not mine. blank address details on the account

now, the kobo site logins for those gmails have fiendish passwords to pass their strong password tests, and were only set up in december. set up on PC because it was easier than doing all the typing on the actual kobos. I cant see how they could have been hacked. no security alerts from google about them being used on new devices, and they were blank accounts. no personal info included.
I am also not sure which, if either, were actually used to set up a kobo. i had terrible trouble typing strong passwords on device and resported to login with google eventually. also i never set up any payment methods or address details. [ the ( abandoned) plan was to give the logins with the devices ).

so to buy a book on a kobo, could someone do it by typing in a card number on the device, without typing any other info? when I login and view the kobo account, everythign is empty execpt for a visa card number for whcih they only show last 4 digits.

do kobo bookstore ever make billing errors.

as at now, I seem to own a best selling book, Little Disasters by Sarah Vaughn, ( which I was able to download on PC ) but no idea how it was paid for or ordered.

someone else, maybe, is missing a paid for book ?