old closed account

I called them in regarding to my old account i had with them, i wanted to pay up the account. They told me that the account is old and it was closed so i can't pay it. They further told me that they will send me the letter. They asked for my email address i gave them, after 3 days, I didn't receive the email, i called them again. They told me that the email was sent i told them i didn't receive the email and asked them to resend it again, they said to me they don't send it twice, please help me i really need this letter.