Replying to Ski boots fit tight

Hey, I know I should probably look into buying new boots but I'm not in the best financial situation as a college student plus I'm only going to get like 10 to 15 days this winter. Anyway my ski boots are 28.5 I thought this would be okay two years ago but they are big for me. I tried on my old 27. And they fit better but they are tight in the toes plus my brother will be using them. Is there anything I can do to make might current boots fit tight. My heel comes out when I move my foot up and I have them buckled as tight as possible. Is there any way I can tighten up the heel area behind my leg and get my heel to stick in the boot making it more firm. Any ideas would be appreciated because I need to figure something out for tomorrow. I have tried two pairs of socks in the past and that is plain awful. Thanks