HUGE pet peeve

Why do we pay for pest control services when they AREN'T DOING WHAT THEY'RE SUPPOSED TO BE DOING?!??  The guy came and sprayed in early March and is due back here in a few weeks.  However, we've had gnats, teeny ants, and now scorpions in the house since.  WTF????  I had to kill one this morning under the dining room table that E was trying to play with.  NO NO NO NO NO!!!!  I'm calling the place today and getting the guy to come ASAP and do a thorough job.  None of this half-assed stuff he keeps doing.