I assume that they lied about it needing adjusted. If it just needed adjusted chances are they would have done it. It takes thirty seconds. I'd go with Coy's idea, they probably didn't want to put money into it.
The clutch cable goes across the engine bay, and attached to an arm on the front of the transmission. It has a plastic nut kind of thing on it that you turn to adjust. (Clockwise tightens it.)