Any ideas on how i can get out of my iphone contract or fix my iphone?

wup, I have an iphone 3gs and ive had it for a little over a month. before this iphone i had another 3gs which i had for almost 10 months. i got a new one because it kept dropping calls and my warranty wouldn;t cover it because of a cracked casing. my new iphone started acting up on me. the screen sometimes doesn;t work espcially when i text. i know the actual screen isn;t brocken because (i know this sounds weird) i put my phone in the freezer as an act of desperation to fix my screen problem and it actually worked. the only problem is that after a while it goes back to normal. i cant replace this iphone because i cracked the casing again( i know im really stupid), but the screen was acting up even before the casing was cracked. any ideas on how i can get out of my contract because the cancellation fee would be around 115$ which i cant really afford. i dont wanna be stuck with my brocken iphone until march of next year!!! can someone please give me an idea on how to get out of this? i know where i can buy a blackberry very cheap and i was wondering if i can take the sim card out of my iphone and have it work in the blackberry. thanks for all the help and any advice or tips on how to fix my phone will be apreciated!!!