I just downgraded my account, proof:
View attachment 2747
using this tactic:
i opened a ticket:
Dear blizzard,
Yesterday my friend gave me a game code for the wow Battle Chest for my birthday. For some reasen something went wrong with the payment, however he did get the code. I entered the code and everything went fine. But this morning I was locked out of my account, because the payment was incorrect or something. Now i can't log into my account anymore. My question is: Can you downgrade my account to the starter edition again so i can buy the game myself?
I hope you can downgrade my account since I put a lot of effort in my account and in my opinion i didn't actually do something wrong.
answer:
Greetings,
Thanks for contacting us regarding this issue

As you request I've unlocked your account now and you should have no issues in performing an upgrade as you see fit.
Regards,