nezadovoljan

1. (of a person) dissatisfied; unhappy
   Radnici su nezadovoljni platama. — The workers are unhappy with their pay.
   Bio je nezadovoljan uslugom u restoranu. — He was dissatisfied with the service at the restaurant.

The cause takes the bare instrumental: nezadovoljan poslom, platom. Colloquial nezadovoljan sa poslom is non-standard.