I've never heard of hiring someone to catch rats. It's too easy, and even fun, unless you're overrun like Big Mo.
Even at Big Mo's place, swarming with rats, a few weeks with traps and poison and you'd be in control.
Exterminators are for termites, or skunks, or something you can't take care of yourself.
Rats, mice, bugs...haven't these DUmbasses ever heard of Home Depot?