Got charged even the transaction was declined

[adrrrrrrrr]

I am a customer at a shop that uses Shopify for their POS. I tried paying for an item through my debit card and the pos system says the transaction was declined. I then proceeded to use a credit card for the transaction. But soon after paying, I got a notification from my bank that says I have been charged on my debit card. 

I went back to the shop and they told me to wait. I waited for a week then I decided to head to the bank to ask for the information on the transaction as the shop told me that the money is "probably" on hold. 

After communicating with the bank, they told me that the money was definitely charged and I should go back to the shop and ask for a reimbursement. They also provided me with a bank statement that shows the record.

But the shop refuses the refund me as they claim that they have only received one payment. Which was from the credit card even though I showed them all the information about the purchase that had.

I want to know if the money is getting stuck with Shopify as the shop claims that they don't have the money with them.

Picture of the receipt

 Picture of the bank statement

[laj_vancouver]

We are a business that uses Shopify and just experienced this with a customer yesterday.

Our customer wanted to purchase an item and split it onto two different payment methods. The first payment on her debit card was approved - the green checkmark appeared on the screen of our Shopify POS Go, our sales associate saw it as well, so we proceeded with the second payment on her Mastercard. Unfortunately, that payment was declined which led to the technical issue of the first payment on her debit disappearing. 

There wasn't a physical order in the system so we couldn't refund her. We advised her to contact her bank and the bank confirmed the transaction was approved. We also got screenshots of the transaction.

We have been in contact with Shopify to try and get this money back, however, it is still under investigation.

Have any other retailers been experiencing this?