A different company creating listing under my brand name

Hi,

Wondered if anyone could provide some advise and best course of action.
I received a call from a custom today that had not received their item.
I was unable to find the order but the customer gave me the details so I could locate the listing on Amazon.

I have the brand ‘Signs And Stickers’ registered under Amazon brand registry program and my business is called Signs & Stickers Ltd.

When I look at the listing it shows the brand as ‘Signs And Stickers’ but sold by ‘Signs And Stickers’ but then the company name and address are for a different company.

Can anyone provide any advise on what, if anything can be done.

Many Thanks,

David