Dissapointing response

Good Morning.

So I had bought some sale items last month I think , so yesterday I was trying to send some back that didnt fit me but the ladies at harties mall refused to take it back saying they cant take back sale items as the sale has ended. My concern is that the slip says I can return until 30th of May but I am being told a different story at the store. What is the process.. I am distressed.