Exchange problem

I have 2 clothing items that I received as gift because it's gift there is no slip but the items still has it's tags on, I went to the store for an exchange\refund and I was told to see if there is something else I like in the store and there was nothing that I liked for my daughter, I told the cashier that there was nothing and asked if I can get a refund or a gift card and she said no i must just take something in the store or get the slip, i told her it won't be possible for me to get a slip as the person who bought the items passed away and she said well i can't assist you then. I told her it's not the first time that i have done an exchange/refund without a slip and i was helped and she just said you must take something in the store to the value of the items cause I can't give you a gift card or refund and walked away.