Cellphone Return Issues

My sister bought me a cell phone last week from Game Umhlanga Store and unexpectedly gave it to me at the airport when she was leaving to go back home. I did not need a cell phone even though I had misplaced my original phone for a day or so but had eventually found it. I did not use the new phone or even register it on any network nor did I open download or use any of the phones features. The phone is still in its original condition even though it was opened at the store when my sister bought it by the cell phone employees. I do not have any use for the phone and wish to return it back to the store and return the money back to my sister. The store is not accepting the unused cell phone within the 7 day period even though Games return policy states : If you are not happy with your purchase you have up to 7 days to return it to any of our stores for full refund.