I think your boot has been softened quite a lot and there is no point in softening them further. The dotted lines usually do the trick. I would never cut the V in the back. The V in the back of your boot is quite big, so there is a chance the flex has changed. That's IMO.
The bootfitter (from what i understood) followed the manual. Everybody can do that! In your situation a REAL boofitter could help you a lot more than your current bootfitter.
So here is what you can do. Check out posts 78 and 82 in this thread:http://forums.epicski.com/showthread...7&page=3&pp=30
Checkracer recommended two austrian bootfitters (real bootfitters). I think you could contact them. They should not be busy this time of year so a visit could solve all your problems. OR you could go in winter (you mentioned you will be in Verbier, Switzerland). Austria is very close.
A real bootfitter will make the difference. And be prepared to buy a new boot
seriously, i think this one of your best options. How many bootfitters (not even real bootfitters) are in the UK???
One of the two austrians could solve your problems (even if they probably don't speak English very well) and you will have a great season.
At least it is an option...