Your friend, who has 10 years of service in HR was interviewed for HR position but was issued Offer Letter as "Asst Manager". Now he has been assigned duties other than HR and he is confused on what to do now.
A query like this, if comes from a person with 10 years of experience, itself is questionable. Moreover, your friend was in HR. How he accepted offer letter that did not mention a proper designation, is a point to ponder. Going further, rather he coming on this forum and raising a direct query, he has assigned this job to you! This is one more mismatch!
Anyway, he may choose new job in HR if he is getting calls for working in HR Department.
31st May 2018 From India, Bangalore