At the end of "reunion" Drusilla and Darla massacre a bunch of Wolfram and hart employees in Holland Manners' Wine Cellar. In the next episode "redifinition" Darla claims that she left them a "Fifteen body memo" in referance to the slaughter.

However, when the report reaches kate Lockley (The thin dead line) she tells Angel it was a case of, "Thirteen Lawyers massacred in the Wine Cellar"

So which is it 15 or 13?

There were infact 17 lawyers (Including Lindsay and Lilah) But since they survived they could not be counted as "bodies"