Unisa's disregards of students

I have been waiting for unisa to resolve my problem of incorrect account billing which resulted in the system to block my results. Its a shame because I cannot register my masters if I do not know if I passed my honours. I have been corresponding with them and they always takes two weeks to respond in emails. the telephone they provided no one is picking it. My last contact from them was an emails on the 17 february 2015 with two conflicting statements. Now they do not want to come back to me and explain which statement do I use as the base of my arguement or querry. According to my knowlegde unisa owes me R500 but the statement 1 says I owe unisa R880 and statement two says I owe UNISA R0.00.