If you were able to roll back time and start again then you may have ended up with a different outcome.
First, ask VM to change the TiVo box to a V6 box. Charges and a new contract may apply.
Second, once the TiVo to V6 swap is carried out and provided the contract terms allow you then ask for both V6 boxes to be switched to the 360 firmware.
Clearly this is all academic after the fact, but may be helpful to anyone else reading who is tempted to make the change.
________________________________
GrahamI'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media, I'm a VM customer. There are no guarantees that my advice will work. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks