Need Help!!! Tracking citizenship certificate sent from cic April

[Divinity]

Hi, My husband applied for a citizenship certificate for our daughter. It was mailed out April 13th and the representative did not receive it . I went to the consulate to see if they would still give our daughter a temporary passport and they said we have to find out what happened to the certificate first but I dont know where to start. Does immigration use regular mail? How do we let them know we didn't receive the certificate? What can we do?