No problem,
You can go to Astrid's page by searching for Astrid Appels under "Find" in the top left corner of any Barnmice page.
Then you can leave her a message. Pls. let me know if you have trouble with that and I'll come up with something else. Oh, also there is a Polish Dressage Riders' group listed among the site groups. Maybe some of them might know, if you post the message there.
Good luck - and welcome to Barnmice!!