Have had the current  T-box for 10 months. First one went back after 1 week, faulty unit. Certainly is a glitchy system, but due to signing on for the 24 month term am obliged to stay. 
Latest issue is certainly an odd one.
Suddenly controlling the volume using the T-Box remote stopped working on seemingly random channels.eg:1,2,3,20,21 etc, yet works ok on other channels e.g.: Food-9, The Box-5 etc.
On the non-resonsive channels the volume icon comes up on screen but no actual change to the volume, its on 100% all the time! Yet the mute button works. Weird.
TV is a Sony Bravia EX520. Since T-Box installation have had several compatibility issues, is this another one?
Had done several T Box reboots  to no effect.

Any suggestions most welcome to resolve this issue.

cheers