Sheet Street below quality products without exchange

I was given a gift, from Sheet street, of a large scented candle in a pottery bowl with three wicks. After burning it only twice the candle stopped working as they had only placed three small tea candles in the middle of a very large candle and not a large wick. I went back to the shop to exchange the gift, however, the lady was adamant that she was unable to replace it without a slip. Of course, one cannot go back to the gift giver and request a slip to exchange the gift, so now what does one do? Apart from having to melt the candle myself and add my own large wick, there is no other option, Sheet street is selling poor quality products and then you get stuck with them.