What are some possible explanations for the complaints, and what actions might the manager contemplate?

A computer repair shop had received a number of complaints on the length of time it took to make
repairs. The manager responded by increasing the repair staff by 10 percent. Complaints on repair
time quickly decreased, but then complaints on the cost of repairs suddenly increased. Oddly
enough, when repair costs were analyzed, the manager found that the average cost of repair had
actually decreased relative to what it was before the increase in staff.

What are some possible explanations for the complaints, and what actions might the manager contemplate?