After my catalytic converter and two sensors are repaired, what else to do?

Lots of dealers get their parts from Autozone,Advance,O'Reilly,Napa if needed..i know several guys/girls who delivers parts to all of the above here,and to Firestone Complete Auto Care also,and to all shops.

That being said , WHAT qualifies your mechanic , to be your mechanic? Does he/she have access to HONDA software updates , and if needed , are they able to do them? VERIFYING proper software , would be my first step , then , I would personally question the original diagnosis , since in 12 years at a Honda dealership , the ONLY Civics I have needed to replace BOTH sensors (at the same time) on , have been the hybrids (and that also included a software update).