UNISA giving no feedback

I have submitted forms to UNISA last year December 2017 for two of my subjects to be re-marked. I am struggling to get hold of anyone to assist me from UNISA and struggling to get any information regarding my remarked subjects for which i have been Billed already. It is nearly time to write my next exam again, where I will be writing these two subjects again and therefor be billed for writing it again as well. I will now be billed R395.00 for remarking of question paper - NOT DONE! And I will also be billed R225.00 for writing the paper again. Unisa needs to credit me for the remark as this has not been done from their side. I have send several emails with no response! I am fed-up and frustrated!!