How to unlock my iPhone?

Hello, I want to know why you refuse to unlock my phone.

The phone was used by another person with whom we no longer talk and I took the phone and I can't figure out the account I know that the account is currently in use What else do I need to send you to prove that the phone is mine I can send you a passport card. and I can send you some certificate from A1 that the phone is my property which should be in English as I guess you don't understand our language 

 Thank you

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