Before calling the plumber, try unclogging sinks yourself.
- Pour 1 cup of baking soda in the sink
- Pour 1 cup vinegar in the sink (white is recommended)
- Pour boiling water
- Use a plunger to make sure it is clear.
I found that when a sink was just slow draining it helped to add water when the plunger was in place to cause more of a suction.