You can not currently add funds to the eshop (at least in America). Eshop cards won't process and credit cards will be charged without adding any funds to your account. According to the Nintendo tech forums this issue will be ongoing untill 5 PM Pacific time tomorrow June 30th.
Link http://techforums.nintendo.com/message/134954#134954
Also, if you are desperate for club Nintendo coins let me dispel some inaccuracies spread around the internet.
1. You no longer get coins for Netflix registration in the American market. Link http://techforums.nintendo.com/message/83106#83106
2. You no longer get coins for Hulu registration in the American market.
3. You no longer get coins for Nintendo video registration in the American market.
4. NES pinball no longer gives you 60 coins only a post play survey for 10 coins.
Learn from my mistakes and you will be all the wiser. (I tried to help one of my sisters get gold status on club nintendo and did all of this.)
