Duplicated online payment

I've bought sneakers online 23/08/2024 and i made duplicated payment I've sent the proof of payments and my bank statement to them requesting for a refund they rep**** and said only 1 payment was reflecting on their side... I went to my bank and they gave me payment confirmation letter that states both payments were successfully paid to their account.

And they said they will ask their accounts to investigate and they came back stating that they only receive 1 payment... I am very disappointed. I lost my money just like that