Please help me with my iphone 13 pro

i'm a new iphone user, i got this iphone 13 pro new from shop , someone helped me set up the phone with email i have password but in between , its says icloud This Apple ID has been locked for security reasons that i should reset it , its asked for two option for resetting ,date of birth or send link to email attached ,which i dont know ,its was the guy who helped me set it up put details there and i have looked almost everywhere for him no luck, what can i do , i dont steal phone i am the rightful owner of the phone , i have it with box and everything, Apple asked me to provided receipt for proof of purchase and i uploaded and the email kept coming that they didnt satisfy ...here is serial number( TN***727) and i can provide password for the email above if necessary, i really need help

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