applying for a visa from outside zimbabwe

Hi
I'm studying in Cape Twon, South Africa. I need a visa to go for a school trip but I am unable to come back to the embassy to apply for it as I am in the middle of a semster here. Can I apply for it from the embassy here in Cape Town or must I send signed forms and the necessary documents back for my guardian to hand in?

Thank you in advance,
Kind Regards.