PLEASE! FWD a copy of the letter, and copies of the logbook pages to the local FSDO that is in the shop's area:
http://www.faa.gov/about/office_org/field_offices/fsdo/hou/contact/Always include the IA's name and certificate number, as well as any mechanic who also performed the "work".
In your correspondance to the shop, at the bottom should have the statement
CC: Houston FSDO
(just so they know they could expect a visit from the friendly FAA)
That is guaranteed to get everyone's attention.
-Brian
