If you know the positions and names of the counterpart departments and contacts of the recruiting unit, write their titles directly; If you don't know the position and name of the contact person in the other department, just write "Human Resources Department of XXX Company:" or "Dear Human Resources Manager of XXX Company:", because this is a general title and title and you don't know. Don't attach too much importance to this link. Generally speaking, resume screeners can't exclude you just because your cover letter is misnamed, unless, of course, your name is impolite.