This is constantly happening to me as well. Today, even though I'm using only my own V6 box and one other laptop, it says I've reached my device limit. Apparently, if two people using the same laptop choose to use both the app and the Web version of Virgin TV Go, it thinks it's two different devices. That's utter madness.
Can anyone help me reset my devices?!
[MOD EDIT: Subject title changed for clarity]