I can't buy sticker from sticker shop. Can you help me???

If you would like help from these user-to-user forums then you will need to provide more information than 'can't buy' e.g. what happens when you try to buy them, does the 'buy' button not work, do you get any error messages ... ?

If you are getting a message to contact iTunes Support then you can do so via this link and ask them why the message is appearing (we won't know why) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption

If it's a different problem ... ?