Bad service

On the 25th of November i called the collections department request a settlement amount for my cell c contract i was given a 15% discount which means i must make a payment R 4484 on the 28th November. Ever since i have been requesting a paid up letter im being transfer from pillar to post. I have send a proof of payments logged cases but still im being told i owe 791 this is totally unfair i will not be doing any business with cell c anymore no has assisted me. Which makes me question why am i still owing becos my balance should be zero im very upset i have wasted so much time calling collections and customer care. The number in question is ***