It had been a few days since I couldn’t make any transactions in the DI shop with my credit card. I removed my credit card payment method and resubmitted it and still failed.
I called my bank and they told me that they didn’t block the Blizzard merchant and my credit card is active and nothing wrong with it. I even made an online purchase with my card today.
So I think my card is fine, and there must be something wrong with Blizzard’s service in these few days.
I am playing on the SEA cluster server.