Little update on my situation.
I was indeed charged twice, well 3 times if you include 1.00 EUR charge. My bank statement looks like this:
24-Sep 1.00 EUR, Blizzard Entertainment - this charge happened when I added a new payment method. It doesn’t show in Battlenet Account Transaction History page.
24-Sep 12.99 EUR, Blizzard Entertainment - this charge happened shortly after I added new payment method and confirmed the same WoW subscription plan. It doesn’t show in Battlenet Account Transaction History page.
25-Sep 12.99 EUR, Blizzard Entertinament - this charge is the only expected one, I was due to pay for WoW 1-month subscription. It shows in Battlenet Account Transaction History page and order status is “Complete” as expected, everything seems fine and I can play WoW.
I googled a bit, even found Blizzard’s Customer Support article mentioning those temporary pre-authorization holds but from that support article it looks like it shouldn’t apply to my case - I didn’t change my WoW subscription plan (it was 1-Month Recurring and I confirmed it to stay 1-Month Recurring), there was no promotion or discount on my to-be WoW 1-Month subscription purchase or anything similar (which support article mentions could be the reasons for pre-authorization holds). On top of that my payment change was just a newly issued credit card (old one expired), credit card of the same type from the same bank connected to the same bank account and with the same card holder name (me).
Reason why I am writing here instead of calling my bank is fear of bank’s support incompetence and possible misunderstandings that would result in them initiating a refund and most likely cause my dear day 1 vanilla WoW account suspended or banned.
I want to say again that I successfully paid for WoW 1-Month subscription and purchase of it is labeled as “Complete” in Transaction History page - my Battlenet Account seems fine, I can play WoW and everything looks good. It’s just about those -14.00 EUR I got charged BEFORE the expected WoW 1-Month subscription payment.
If someone from Blizzard’s Customer Support could look into my case and confirm to me that 1.00 EUR and first 12.99 EUR charges are indeed “temporary pre-authorization holds” and not an actual payments and that those funds will be released by my bank in upcoming hours/days, I’d appreciate it a lot - because as of me writing this my bank statement still shows hold on 27 EUR (combined from those 3 charges) while I expected it to be simply 12.99 as it was the case months and years before.
Also, consider communicating this situation better to your customers. During the whole process of payment update on Battlenet Account page I was never told about these temporary pre-authorization holds, on contrary I was told TWICE that I will NOT be charged while my WoW subscription is active and before I am due to be charged for the next month as expected.
Thanks in advance and have a great day.