AirPods fake?

I bought airpods from a private seller in Israel and after a while they started doing problem, disconnected and others, when I took them to the lab in Israel (I-digital) they told me they are fake.

I have a serial number and also I see them in the iPhone and in Apple care. Serial number : LN***YJ5

What to do???

Please help me.

[Edited by Moderator]