I feel for ya. I have had 5 Technica shells all in the Icon range since my TNT's. The TNT was a great boot for Technica. Latter boots seem to experience packing out a lot. So bad that last years ICON I went down 2 sizes to try and hold my heel. The problem is they are wide to begin ( I am a C width) and 1/4 inch longer in the right, to accommodate the length they get so sloppy in the shaft and heel area after 15 days of skiing, and just seem to keep going.
I hear they have fixed some of the packing out issue in the Diablo, but just did not want to chance it any longer. I went back to a Nordica which was tight for me many years ago, but now everybody is opening them up. I went with a Doberman Pro 130 which is a hard flex for most; ya could try a 110 if you could find it. This boot packed out at less than 7% and did it all in two days, hasn't moved since, got about 30 days on them this year. There is no Shaft adjustment!! Fits like a glove, and not that cold in deep powder! Remember boots are like women, everybody wants to get in a new one, few will wanna stay forever!!