I've been getting terrible battery usage from my iPhone 3GS. It barely lasts through the day (12 hours at most if I'm lucky) with 3.0.1, and now with 3.1, it lasts 8 hours. My question is, if I take it to the Genius Bar and tell them my situation, will they give me a replacement? I bought my 3GS when it came out back in June. I also have AppleCare. When I had my iPhone 3G, it would last a little less than 2 days... Also, since updating to 3.1, I haven't received any of my voicemails. I have to manually check my voicemail by calling my number from my cell. I had 7 messages I never received via visual voicemail. Any suggestions on that as well? Thanks in advanced.