How can I report a problem with a purchase App?

Copied from http://www.apple.com/support/iphone/assistant/application/#section_7 :

If you are still encountering an issue with the app, you can use the App Store to report your problem.

Open the App Store on iPhone and locate the app.

Scroll down and tap "Report a Problem."

Select your issue and any additional comments.

Tap "Report" to submit your issue.

there are some purchase that i didn't authorize on my account how can i resolve the issue