In cement driveways a very cheap way to do a repair yourself is to add some gravel. The gravel mixes with cement or old slabs very well filling any holes that occur. A colored gravel does perk the driveway up and helps to restore the driveway. You can do this repair yourself economically.
Buy screenings (dust like rock particles that harden together when exposed to water), and spread them evenly over the low spot. Moisten the area, and then smooth out the top.