Someone has logged in to my ebay account and changed my password, i think i know who it was.

Ebay supplied me with some numbers ip address or something.

Can anybody tell me what i should do with these numbers.

I am assuming i will be able to tell which workstation it was altered from with these number's.

Do i get in touch with the police or just let ebay know about it or what.

I changed my password again now so they can't access it again, any help or info would be great thank's in advance.