Unable to assist with a basic account

Very unprofessional and rude company. A doctors' receptionist accidently handed over an account of my grandfather. Very eager to send statements and want payment but as soon as the doctors' receptionist rectified the problem, the company refuses to write me an email that my grandfather does not owe them any money. Even though Colmed confirmed on the phone that the doctor withdrawn the account, they refuse to put it on email. Thinks it is a big joke and laughed at me.