Incorrectly billed

I won upgrade woth them before which was the competition they running but now all of a sudden they making me pay for it... How can i pay for something that i won.... Where the hell am i suppose to get R1756. 00, i called them they said there was a reversal i should send statement to show of it was a glitche on their side, i spoke to a lady named Khayakazi who said the problem was on their side and i will pay the normal amount... Another lady called again and said the statement i was told was not true.... Very unprofessional.