Cant mute Sky Soubdbox

[devilsadvocate]

Just had a new Sky Q 2TB box installed as the old one stopped working, SKY engineer fitted it themselves.  On my old box I could control my SKY Soundbox with my SKY Q remote, including muting it.  On the new box I've synced the remote to the soundbox again and can control the volume, but I can no longer mute it.  Also, I used to be able to change the input using my SKY remote but this doesnt work on the new box either.