Dollar General review: Return problem

I bought a Christmas decoration from the Dollar General on 3421 Hwy 301 S in Hernando Mississippi on December 16th. The product was damaged. It was a set of gnomes and it had 3 left hands instead of two right and two left. I returned the item the next morning. I was told the return would go back on the card I used to make the purchase. When I bought the item it was on sale for 50% off. When the clerk returned it it was giving me the full price. I told the clerk that but she said well this is the only way I know to do the return so it looks like you are getting the full price. She asked to keep my receipt so that she could ask her manager how to do it right in the future. I never got any refund which should have been 15 dollars plus tax. I went back another day and asked about my return and she said it takes a few days. I mentioned that I was worried because I had not records since she kept my receipt but she assured me it was in their financial records.