Why can't electronic repair shops do their job correct.

I drive down to Haverhill Mass to pick up my Onkyo. 52 miles one way. Get home, hook everything up remote is now working; great!. Effing volume knob is not

This is now not an Onkyo issue this is an incompetent tech issue. Damn this crap pisses me off. I don't need the manual volume control, but it should work. It worked just fine before I dropped it off. What would you guys do? Drive back and make them fix it, open it up and see if a cable is just off? What do you think?