UPS is being UPS here.
They’re abandoning packages, then sending her a bill for COD as if she accepted the package but didn’t pay.
The fact that if she digs in and fights it she can eventually dispute each charge is somewhat separate from UPS and their collections contractors harassing her about the ‘debt’, or the new packages that keep showing up.
Yeah, I had to un-quit Whatsapp when my siblings-in-law moved to Argentina - because Whatsapp is the main communication platform for a lot of Argentina and that’s where all the various family chats moved to once the in-laws no longer had local phone numbers or reliable SMS service.