Usage patterns
〈事〉の担当者the person in charge of (a matter)
I'll check with the person in charge of this matter.
担当者に連絡するto contact the person in charge
Please contact the person in charge for details.
担当者が対応するthe person in charge handles/responds to (something)
The person in charge will respond to the customer's questions.
担当者を変更するto change the person in charge
Due to sudden circumstances, we had to change the person in charge.