What can clear a VERY clogged drain ?

Kitchen sink is CRAZY clogged ! Hired a plumber who snaked and it worked ok for a couple weeks then clogged again. Purchased some ZEP and it seemed to work like a charm but now its completely clogged again ! Used an entire bottle of zep, plunged and still no help ! Its not my main line because the bathroom fixtures all drain in a heartbeat...what works ?!?!?!?! Im seriously getting pissed and i cannot afford another plumber that just "patches" the issue :(