Pull&Bear Refused My Shoe Size Exchange Because I No Longer Had the Receipt

I purchased a pair of white shoes from the Pull&Bear store at Istanbul Akasya Shopping Mall on the 23rd. After the purchase, I realized that I had accidentally bought the wrong size. Today, I returned to the store to request a simple size exchange for the same product.
Unfortunately, my exchange request was denied because I had thrown away the receipt and the product barcode. The store employees informed me that they could not assist me in any way without those documents and stated that I would need to contact online customer service instead.
I was disappointed by the lack of flexibility and willingness to help, especially considering that the purchase was made very recently and I was not requesting a refund, only a size exchange for the same item. Rather than offering a practical solution, the matter was dismissed solely due to the missing receipt and barcode.
I am requesting assistance with exchanging the size of the white shoes purchased from the Akasya Shopping Mall Pull&Bear store and would appreciate a reasonable resolution to the inconvenience I have experienced.