over charged

i called car track on the 24th August to transfer a tracker device from my old car to a new car, a consultant from car track advised me am going to be charged R850 I refused telling her that's lot of money , then said will speak to his senior for discount then came back say I will be charged R570.

on the 20th of September when checking my account I was charged R850 when I called client service no one is willing to help me, there was even lady from accounts who was very rude to me telling am say name of the person who was helping ( I must stop saying they) I was transferred from one person to other, I even called yesterday other lady said person who is dealing with my account will call me back I still haven't received a call.