The title says it!
Customer care responds to a complaint, but it does NOT IDENTIFY WHICH COMPLAINT!
When I report a Yahoo account for spamming or being used to collect replies from phishing/spamming the acceptance screen gives me an incident number. Yahoo's customer care only has a reference alphanumeric designation. It does not reference ANY incident number. If I report Two yahoo accounts the same day (I have) I have no idea WHICH they are referencing!
I include the FULL Headers and message content that Yahoo provides, yet I am sometimes asked to provide it AGAIN, and I have to GUESS as to which message they want the information from.

Thank you for contacting Yahoo and reporting possible abuse on our network. We take such reports very seriously, and review each and every report we receive in accordance with our Community Guidelines and Terms of Service to determine appropriate action.

We reserve the right to terminate or take other action on accounts of users who appear to have violated our Community Guidelines or Terms of Service. However, consistent with our Privacy Policy, we don't disclose the action taken on another user's account with a third-party.

We appreciate your patience and understanding.

Best regards,
(Name removed)

Yahoo Customer Care

ref:_(omitted)
------------------------------compare to:
Microsoft Online Safety
Thank you for letting us know about the questionable email you received.
We found it violated the Microsoft Services Agreement http:// (omitted). The account is now suspended.