*****ulant calculation of % discount - amount and % differs

I bought E/B black EDT for R420.00 with a 30% discount. The till slip shows 30% of ' R84' - wich is a 20% discounted amount. Tge 30% should be R126.00 When I called and logged a complaint that the amount and calculation is fruadulantly calculated, I was told by Dalene Solomons from their Head office that they cannot refund my account and that I have to come back to get the difference. I told her that I'm not planning on driving there and loose more money on petrol. Or I can take my rewards card and slip to a Clicks for points. This is clearly ***** as customers does not calculate the % discount on each item. I expect a clear reason for this calculation and money plus interest to be paid to my account which I provided on my email