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Hey Michael! Very good and creative tips from Moosa and Umar about trying to track this down, so I'll just respond to the part of your question dealing with what to tell clients. 100% consistency may not be a realistic goal for any business, precisely because of a scenario like yours in which old or bad data ends up on a directory you just can get connected up with. In such cases, judging the overall importance of the directory in question becomes key. If the directory is ranking in the top few pages for your client's name, then incorrect NAP there warrants making every possible effort toward resolution. But, if it's an obscure result, make normal efforts and then let it go at that if you can't find any way to correct it. Document your work for clients and pre-set expectations that you are shooting for high consistency, but not perfect consistency. Some of the smartest citation building experts I know have told me that 100% consistency is not only frequently impossible, but not even actually essential. Hope this helps!