iphone4 problems in touchscreen

Hello everyone,

I´m from Brazil and i bought one iphone4 in Canada - Montreal´s store.
But since I started to use that I have problems in the last line from the touch screen.
I can not select itens like answer call, safari, phone, ipod and all icons in that line.
I can not change my iphone4 here in Brazil.
And I can not talk with any advisor in Canada Apple Store...
Someone can help me?
Do you have an e-mail that i can talk to send my iphone´s problem to a new one???
Tkss,

Mayra