I’ve tried to wait 20 mins for it to go away as the related article suggested. But it hasn’t gone away and I can’t purchase any packs
To remove this purchase lock you’d now need to contact Customer Support who will check the payments. https://eu.battle.net/support/en/help
Do make sure you log in on the same device you made the purchase on and wait for at least 20 minutes (I recommend 30 just so it’s easier to time). Sorry for this problem happening though and hopefully it can be lifted by Support when you contact them.