Net Zero - trying to cancel service for my mother who is deceased

Net Zero - I have tried for 3 days now on hold forever! Never a live person, no info on their web site except the phone number that no matter what option you pick, you can not get a fax number or address to mail information to cancel my deceased mothers account. If you have a fax number or an address to where I can send her death certificate and a cancellation letter, it would be most appreciated!!! Thank you!

Suzanne