In reply to StuartCJones: Scarpa always seemed narrow to me but,,,you are already using them , next would possibly be salomon,
I have used at least 5 different brands of winter boots alone.
Footbeds are a good investment, go to a good shop with good fitting standards, sometimes ski shops are very good at this, especially if they sell walking boots aswell.
the problem does sound like a volume issue rather than a size issue, it may seem obvious but when you find the solution it will feel "right",
some insoles are good for reducing boot volume, I use the Scarpa red insoles (very very similar to superfeet green but 1/3 the cost) but these are for a different reason(I have small heels and they stopped a lot of slop in the rear which helped cause blisters),
stuffing a bit of old rollmat behind the tongue (as mentioned) could help keep your foot back
cheap solutions,,,,no need for new boots imho