Somebody tried to buy something using my Apple ID, I want to cancel that order

It is a phishing attempt, a very, very bad phishing attempt.

Delete the email.

• Apple does not include document, or PDF files to download.
• Apple would not refer to you as Dear Customer, Dear Client, or anything other than the name on file for your account.
• Apple would not have such horrible spelling or grammar. 
• Apple would not send a message to “Undisclosed Recipients”. 

It is a phishing attempt. Do not respond. Do not divulge any personal or financial information. You can use the address below to forward the suspect email message, as an attachment to Apple.

reportphishing@apple.com

If you provided your Apple ID and password at the bogus site, change your password immediately.

  https://support.apple.com/en-us/HT201355

The links below have information to help identify fraudulent emails.

Identifying legitimate emails from the iTunes Store

https://support.apple.com/en-us/HT204759

How did you know?

You got an e-mail?

Did the e-mail addresses you with your Full Name?

If the e-mail addresses you with Dear Customer, Dear Client, Dear your-email-address, Dear Apple User, ... or something similar then it's 100% scam sent by criminals.

You’re welcome.

Stay vigilant, as the scammers are always trying new things to steal your personal and financial information.

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As stated, Apple addresses you with your Full Name, NOT Dear Customer.

It is a scam.