POOR SERVICE AND NO RESPONSE OF MARKING ASSIGMENTS

My daughter Caylin has been registered for N4 Bussiness Studies, before the cut off date for her assigments we submitted a re write of one of her assigments . no response was given and i have been following up since April but no one is coming back to us. she can only now write 3 of her subjects in November because this rewrite was not marked , how can this be her fault as we gave evidence that this was summitted a month before the curt off date for assignments, i have been emailing since but no one came back to us. i also asked a progress report but nothing was received but every month they asked when is payment going to be made, i withhold the last installment of R800 as i need this assignment to be marked and that she can write this module with her other modules in November