Hey there,
I bought wow sub on 2.8 and everything went well. Received an email that sub was added. I was playing with no problems that day. When I wanted to play today I noticed that it says my sub has expired. Looked up in my email that yesterday, 3.8, I received an email which says my sub has been frozen due to out of date billing informations. Now what is this? When I follow the link provided in that mail, it transfers me to the page where I can reactivate my sub. I follow the process but nothing happens. My money are already gone from my bank acc and no game time availible.
Until now, I was playing more than a decade without any similiar issues.
Please, fix this 
It can be that your bank requires additional authorisation or has declined the payment hold after deeming it potentially fraudulent.
It’s best you take a look what the status is of the bank charge.
If you need additional help due privacy they cannot assist you over the forums but you can contact them here with the (failed) payment orders.
https://eu.battle.net/support/en/help
Judging from the displayed warning message - it sounds like the credit/debit card on file may have expired (as they all do, every few years), and the bank (quite correctly) refused to process the payment targeting said expired card. Setting up a new payment profile with your current payment details and using that one for your subscription would most likely solve this.
With that said: as this isn’t a technical problem per se, we’ll now close this thread.