BlackBerry Curve 8530

I recently got a Curve 8530 from Sprint. I never had any problems with my old Curve. (until I dropped it too many times, coincidence maybe?) At first it worked great, but after a month or two it started cutting out and dropping EVERY call made or received. After complaining to Sprint several times, they offered me a free AirRave. Now my phone works great at home, but this doesn't solve the problem anywhere else around town. Today I found out a nearby friend with an 8530 has the SAME problems. This makes me think my phone is not an isolated case, and there must be some signal/compatibility issue in my nearest tower/switch. What can I do about this? Can I make Sprint take this phone back and give me something else? I love my Blackberry for its features but this kind of service is unacceptable.