Please email your account information to firstname.lastname@example.org or, call them at 855-463-9333. I'm going to guess they accidentally sent the return box to your old address and, you need to contact them ASAP to get it resent to the right place before you get billed for unreturned equipment.
Hello Alison, with this being a “public forum”, I have edited your post for your privacy. We certainly want to get this issue reviewed and taken care of for you as soon as possible; you should have received the lease return boxes 7 to 10 business days after disconnection. Please send us your account and contact info to email@example.com. Or give us a call at 866.945.3258. Thank you