I just had to renew my passport through the US National Passport office.
I did not pay a third party for an expedited passport service, I just went to the Statedepartment.gov web site, printed out the renewal form, filled it in and sent it to the US Passport Office by overnight mail on Friday, January 25th.
They signed for it on the 26th (a Saturday, I was sure to mark "signature not required" for their pickup as it is a PO Box).
I got an email from them yesterday saying "we have processed your port, expect it to arrive by February 4th," but I just got it today. A total of just seven days.
I did pay for expedited service from the government office, which includes overnight delivery on the return.