Bought wrong Region version

I buy War Withing for US server by accident and i wanted for EU, can i get some help please ?

If you’ve not logged in or used the product otherwise yet, you can generally auto-refund using this option for the US:

https://us.battle.net/support/en/help/product/wow/166/1152/solution

Then rebuy TWW here:

Make sure it is paid in €uro’s.