You aren't SOL. The boots you were renting had been worn a lot so they were already packed out. You have to wear the boot a lot to get it to pack out. Everyone's boots are going to be uncomfortable the first few times they wear them, just because there is so much fluff and cush in there, they are tight at first, and then all that stuff breaks down. I always recommend wearing your boots one whole day in the house, just watching a movie or something. You can also play with the lacing- your first few days don't lace up the liner. Then when your foot is used to that, you can lace up the liner, but leave the toebox a little loose. Soon, you'll be able to tie up the whole boot regularly, but until your foot is used to it just keep playing. I usually spend a few days just riding in my new boots for just a few runs before I have to change them back to my old ones. Having them a little too small now is better then just right, because they'll be too big after just a few days!