I want a refund

I made an order on Sunday (16oct 2022) and I added another product cause there was a promo code and when I was in checkout realized that the promo code was not app**** went back a few moments laters I got charged and the order was placed tried contacting them telling them that I didn't place the order there was a mistake they told me that they can't cancel the order theres nothing they can do about that and the worst part I didn't receive one of the items and I want a refund for the item cause it's been over 4hours