This is an example of a mis identified mouse problem.  The home owners were seeing droppings about and having some damage to some food packages.  The earlier pest control company placed out "Mouse Bait" which was readily consumed and after a few weeks were called back to place out some more and after another month was called out again.  The homeowners themselves were able to determine that something wasn't right.  The bait continued to disappear, though the amount of droppings never really ceased.  The two clues that says roaches instead of mice is One, the droppings.  Roach droppings will have ridges that run lengthwise where a mouse dropping will be round.  Two, the seeds themselves have not been eaten.  Mice would have eaten the seeds leaving nothing but empty hulls behind, where as the insects just ate the bait material that the seeds are mixed in.