Call Rogers, ask to speak to Loyalty Retention and explain the situation (my phone is constantly freezing, I'd like to upgrade to an iPhone, what can you do for me) Be firm, but polite (i.e. don't let your frustration out on the agent). If the first L&R agent you get gives you the run around, hang up and try again.
You might want to take a look at this thread on HowardForums:
http://www.howardforums.com/showthre...w-can-i-get-it
The other option is to go to kijiji and see what a used iPhone is going for.
Hope that helps