Refund pending

I went to purchase a few items, I gave the lady a card and she said that it didn't go through for some reason. I then gave her another card and she charged it. I checked my bank app I noticed that they have changed me twice and I told them immediately. It's been a month and I am told that they can't not find the money and my statement that I have sent them clearly shows that the money has gone off from my account.