Can I Downgrade My Firmware?

Can I downgrade my firmware? I had an M250 that I was really happy with, but I stepped on it and unfortunately cracked the screen, so I had to buy a new one. But this one is ■■■■! The volume levels are way too low, it takes too long to skip between tracks, and the sound quality is shocking! I think this may be to do with a possible frimware upgrade, so is there any way I can downgrade?
And also, is there a customer support number for Australia? I can’t seem to be able to connec to the ones on the back of my manual.

Are you using this number - 1800 793 652 - to try to get Tech Support?