This betting site is using my domain extension in their footer

Hello my fellow domainers

Recently I noticed that someone has registered BETBIG365.AG but in the footer they have:
© 2019 BETBIG365DOTCOM, All Rights Reserved.

The DOTCOM I own for many years and is part of my small portfolio. I have reached out to them and asked them to correct it a few weeks ago but it seems like they are ignoring me.

I would appreciate your input and advice how to go about this next. Thank you

This betting site is using my domain extension in their footer