False coupons/False Marketing

I bought Furniture at Lewis and it came with a coupon of nearly R700.00 coupon voucher funny enough it was a ghost marketing strategy from Lewis to hook customers,Despite of several attempts that i made to claim the coupon i was turned down with lame excuses.I even logged a complaint and nothing has been done about it, The Graskop branch manager tells me this\my RCC asked me to check whether there was a markdown on the goods sold to the customer or not