Orion Mall Metro Shop Scam

I bought goods for 4K and made the payment. For some reason, it didn’t update the retailer account. I showed my bank statement as well but he didn’t agree and I didn’t get the items I bought. They asked me to make the payment again, to which I refused since in case one more transaction fails, they still won’t give me the money back. Finally, I just left without the good since the shopkeeper was adamant that I will get the refund automatically back from the server within few hours. What to do in case I don’t get the amount credited back? The shopkeeper said that this issue happens very frequently.