Once again, if the Zipfit liner they are trying to sell you is SILICON, run away. It's simply too stiff and too harsh on your feet. Raichle and Intuition are comfy......with plently enough support for carving....and both can be reheated. ZipFit silicon is a one-time only fitting.
As for your shell, it sounds too big. Doesn't matter what size liner you cram in the boot, the shell is too big. Liners are meant to move, shells aren't. Do a search in the forum for "shell fit"....