Amazon changing product information incorrectly

We were selling B003N7WR6W as a single item. The seller central information is a single item, or so we thought, until a customer gave us negative feedback saying he should have received 3 bottles. He then sent a screen shot of the product page and quite clearly, the picture has a superimposed label saying 3pack. When you hover over the picture (zoom) the picture on seller central that Amazon says is being used (without the 3pack) is displayed. The description on the Amazon page says 1 bottle and the £/l is correct for a single bottle. It’s the picture that states 3pack. He now wants to return the item - lost shipping and return costs for us and the dreaded negative feedback. Any suggestions for me?

This is not the first time that Amazon have changed product information on the fly causing pain for sellers.
In the past we were selling a popular item as a single unit using the barcode for a single product (and the price). Overnight, Amazon changed the item from 1 to 8 units. We walked in to loads of orders - thankfully we picked this up before too many problems, but loads of cancellations and angry customers (who doesn’t love a bargain)