horrible service ana not treated fairly

i have a huge problem with post office in durban russel street ,i mailed my assignments on the 10th of june this year n yet my school hasnt recieved it till today . today i went post office to do follow up on it and they african guy on the door said nothing they can do if it was an odinary mail i ask for manager he came and made me look like a fool infront of every one implyng that its my negligance that i chose ordinary mail.so i can fill the enquiry form when they wont respod to me its not his problem .i hv never been so disrepected .wherelse ag who assisted me did the wrong thing cz he said i must give my envelop to him he put it behind the counter which i believe i was suppose to throw it on the box my self but he insisted i gave it to him his name was SELVIN VENCATASU. PLEAS ASSIST ANYONE. it took me months to finish my work now post office lost it apparently they cant do nothing about it.