Was it sent with tracking? We mailed ours on 3/4 at 4:45PM from Charlotte, NC to Philadelphia. They show as received on Sunday 3/7 on USPS. Then, they finally showed up on the Passport Status check site (after 2 or 3 calls) on 3/23 and show as processing.

If you mailed on 1/27 and have proof of delivery, you should call the National Passport Center and ask where your application(s) are at. Has your fee check cleared?