Where to send my payment by mail

Hi,

I closed my account and have a final bill. I wish to send payment by mail, but the payment address is not listed on my bill or anywhere online in my account. I see this question has come up a lot in the forums, but there is no clear answer. Got hung up on by the Billing department, and can't get through to the Mobile team since my account is closed, and apparently, the office is closed (even though it's 24/7 seven days a week?). Please advise. 

Robert