I will be flying from LAX to CPT and returning back from JNB. I would like the maximum layover time (an overnight) both going and again returning home.

I was told by an agent that you can't stay more than 24 hours or it's considered a stop over yet on this site: http://matrix.itasoftware.com I see several KLM and AF flights that have longer than 24 hour stopovers. I'm fine with stopping at either Paris or Amsterdam as I don't sleep well on planes. Unfortunately I can't book on this site, and it says to print and take to a travel agent to book. (do brick and mortar travel agents still exist?)

So why is this listed as an option if it's not allowed? or is it ?
Thank you.