Vodafone STB & Soundbar

I have a neighbour who has a Vodafone STB who purchased a Soundbar and installed as per instructions with Soundbar which referred to Vodafones STB

All works sound wise but on the screen he gets a popup with the heading of the HDMI port and it wont go away. He can delete it with remote but it pops up again a few minutes later. If he stops using Soundbar all works fine.

Any ideas?