I have sent out eamil to OLUInquiries@dhs.gov
here is one I sent out
Dear Sir/Madam;
I am frustrated by my EAD renewal which is processed in NSC(Nebraska Service Center), my friend's case was in TSC (Texas Service Center), he got approved quickly. As most of my case and my family case are in NSC, I paid close attention to the processing time frame at NSC in comparsion with TSC. I got negative feeling about the NSC , it is low efficient, slacking, reckless . I hope my feeling is not bias to NSC. I did some research online, which is not include those website with language other than English? If it is true, who will care about this? The follows link is for your reference. Thank your time for reading my email.
http://www.endlesswait.com/i140/uscis-nsc-tsc-differences-how-does-this-make-any-sense/
http://boardreader.com/thread/NSC_vs_TSC_16lvX55xg.html
http://www.immigration-information.com/forums/i-140-petitions/4637-nsc-processing-vs-tsc-processing.html
http://www.trackitt.com/usa-discussion-forums/i140/46472971/why-is-nsc-so-slow-in-processing-i-140
http://www.trackitt.com/usa-discussion-forums/i765/574101639/ead-renewal-nsc-applied-between-05-05-to-05-10-join-here
http://www.murthy.com/news/n_nscexp.html
Best,
Alex
If you have more evidence, please add it here Thanks