Where to send box from Marrakech to Agadir?

I'd like to ship a box (a suitcase, actually) from Marrakech to Agadir and have it kept securely for me until I can collect it several days later.


I'm thinking of using Supratours Messagerie. Do they have an office beside the gare de trains at Marrakech? Or do I need to go somewhere else. Thank you very much.