store exchange without receipt

i was really not happy with jet store in eastgate,i had a return cause the leggings didnt sit well on me,all i wanted was an exchange not cash refund,they could see the item still had price tag,but misplaced the receipt and the hardless cashier refused told me how she cant help me need to go look for a receipt i really fail to understand ,what if one gets a gift and want to exchange due to has the similar item will they had to keep due to no receipt,thats perthadic jet eastgate please train ur stuff and teach them retail store procedure