Tell the rat company about the rats in the house. They will tailor a rat control program for you, perhaps using rat poison or setting rat traps. Be sure to accurately describe the situation of the rats in the house so that you can get an accurate quote.
Be sure to think clearly before using the rodenticide or other chemicals recommended by the rodent company. If a child or pet accidentally eats rat poison, they can be very dangerous and may even die.
Tell the rat exterminator to clean up the poisoned rats. If the dead rats are not cleaned up, they will emit a foul odor. Most rat exterminator companies clean up rat carcasses for free. If you are extremely disgusted with dead rats, it is best to ask in advance, so as not to have to do it yourself. Hopefully, the rat exterminator you've found will take care of everything from start to finish.