Returned but no refund

I purchased a sneaker for my son on your website during Black Friday, Your website confirmed there was stock. I’ve gone on your website today to track my order and it’s showing “Returned” absolutely no contact from your end I was only informed once I contacted your call centre they couldn’t fulfill the order which I have already paid for this is unacceptable had I known there was no stock I could of easily taken advantage of other sales!

Please rectify this matter I expect something to be done because personally I feel this kind of service is unacceptable and I refuses to accept