Mice/Rodent Problem in Home -- Stuck in Walls

[Jessica F.]

I own a duplex in Philadelphia and my tenant downstairs calls to tell me that they have a mice problem--they can hear them in the walls and catch them in the kitchen and basement. I have been inside of their unit several times and they are not the cleanest tenants--often finding food, crumbs, dirty dishes, trash etc just laying around the house. I put down some traps in the home (kitchen and basement) to help get rid of them.

I've live on the 2nd floor and I have never had a rodent, bug, or insect problem--until recently. I've noticed a rodent problem but they appear to be stuck in between the walls of my home. My contractor says that they must have ran up through the pipes from downstairs. They cannot access my unit because all of the holes and corners are sealed up and I keep the home clean but the noise drives me insane because they are scratching away in my bedroom closet and I am paranoid that they will scratch their way inside.

Is there anything I can do to get rid of them scratching away between the walls of my home? is there an affordable fix or resolution without having to spend hundreds?