RETURNING AN ITEM

I bought a jumpsuit for R1299 and then later I decided to return it to the store...to my surprise the item is on sale and now its R459.00.The store manager is refusing to give me a gift voucher to the value of R1299.I will not accept that because I bought the item cash and even the stylist that was helping me knows that I paid R1299 for the jumpsuit. This is not the first time I'm returning an item that is on sale. The previous manager Clint manage to help me the last time, I just feel the current manager Lundi Mseleni is just not willing to help me because I even I asked for the area managers number Shani Wood and he refused to give it to me hence I'm taking this route .Can someone please assist and call me back.