I would take it to another dealer.I have worked for many, and they usually cover this type of thing under warranty, as having something fall into the heater is mostly the lack of screens to protect from this.They are obviously not wanting to cover this, and you must trust them to give you the actual cause of the problem. They will get 400 from you and maybe still bill Toyota as well.The salesman or sales manager you bought the car from may help in this case, as they want you to buy another one from them.If they don't give you satisfaction, I would phone the Toyota number in your manual and complain.This is wrong!