I forgot my passport at home. What can I do?

This is a very serious mistake!
Not even a verified copy can help you. Immigration require the ORIGINAL passport/birth certificate of a minor and more.

If you get to Durban early morning, we can assist you if required and provided we can spare a staff member at the time.
Try to get someone to go to your home.
Let them get your passport and take it to the airline's airport desk you traveled with.
Speak to them and ask if they could bring it to Durban Airport. Get their name and the name of the person in Durban along with phone numbers.
9/10 they usually oblige. 

YOU WILL NOT BE ABLE TO CRUISE WITHOUT ORIGINAL DOCUMENTS!