IBO (International Brands OUTLET) *****ed me of my money. They stole from me

I have bought the red all Stat sneakers from IBO INTERNATIONAL BRANDS OUTLET online and the size was too big. I informed IBO and they told me they don't exchange they can only return the items. The sneakers were collected and they confirmed receiving the sneakers and they asked for my banking details promising to refund the amount into my bank account and they didn't, to this day they went quiet on me. They refuse to pay my refund