I don't know exactly why but my phone authorised me not through the
international site of Audible but at the British one. The purchases
at these two are not reciprocally visible, so I had no idea that I
had been paying 8 British pounds a month for a subscription since
February! That's a shame, but I discovered it only this morning
thanks to my bank's mobile app, which noticed me about my
subscriptions expenses. Well, at least they gave me some credits
every month in exchange, and now I can download several audiobooks
with no extra charge. I was sure that these credits came free and
even wrote about in here in May. I supposed that Audible had separate
accounts for web and mobile versions and for the latter they gave
away credits with promotional aims. Unfortunately, they have
different accounts for the UK and international sites, and my books
belong to the former who the hell knows why.
