Does anyone have any ideas on updating firmware on Sennheiser MM 450-X?

These expensive headphones sound fine but there is almost no noise canceling. I Also have a pair of cheap, older PXC310 with NoiseGard 1 and those DO provide quite good noise canceling.  This despite the NC on the 450s being NoiseGard 2
Nowhere is it suggested that there is anything wrong with these later, significantly MORE expensive headphones, other than the el-cheapo speling.  In fact the reviews say the NC is quite good
I can't find anyone at Sennheiser USA who can be bothered to give me any clue as to reinstalling the firmware so i wondered if anyone here has any ideas on where I can find it and how to re-install it?