How can I refund to steam wallet or upgrade my account?

I used steam store purchased 300 points and want to upgrade to the Lord of Ogham Supporter Pack, but this pack cannot be bought with points. I would like to request a refund to my steam wallet so I can purchase it from the Steam store,or could anyone can upgrade my account to the Lord of Ogham Supporter Pack，please, I want buy stash,only three days left!