I got charged for in app purchase and please return my money back!!

I doweloaded this free app and I got charged for $8 in app purchase. Which I never ordered.

I got email(invocie) from Apple few days ago.

Date: 01/10/13/07:47 AM

Order: M******JWZ

Inovice: ******

Please refund my money back. I never want this and never order this.

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