If you just made the purchase you will need to let it go through, then request a refund. They can’t refund it while it is processing. Once you do that, you can buy it on the right account.
DO NOT play the account you accidentally put the sub on or it will invalidate the refund.
Refunds are partly automated to help folks get them faster. If your account meets the refund criteria, it will automatically issue it for you. If not, you have to re-open the ticket to get a GM to manually review the refund request.
Here is the Refund Policy:
We’ve posted this policy to make our refund philosophy clear around purchases made from Blizzard on Battle.net. This document is part of our official Terms of Sale.
Regional Limitations
Note: This policy does not apply in Korea, Japan, or in mainland China. Please see local documentation for those regions’ practices.
Our Philosophy
We believe in our mission to create epic entertainment experiences, and we want you to feel confident you’re getting the product and support you expect from Blizzard.
If you change your mind about a recent purchase, or if you haven’t used it, we’ll try to work with you on a refund.
We may withdraw refund eligibility for abuse of this policy. The same goes for violations of the In-Game Code of Conduct or the End User License Agreement.
How to Request a Refund
You can request a refund using our support site and selecting the relevant game or order. We can only provide refunds for purchases made on our own platform. This includes purchases made through the Blizzard Shop, the Battle.net App, or within one of our games.
We will typically refund purchases to the method of payment used for the original transaction. In some cases, such as those where the original payment method cannot be refunded, we may provide the refund in the form of Battle.net Balance.
If the automated service doesn’t address your needs, our support team is available to help.
Subscriptions
We’ll refund any unused World of Warcraft subscription within 14 days of the purchase.
We won’t refund subscription time lost due to a suspension and/or permanent account closure. For permanent account closures and suspensions longer than 15 days, we will cancel upcoming recurring subscriptions.
(Mira note: This means the sub has not been used at all, not that that they refund unused time on it)