A few months ago, the signal quality really went down on my iPhone 5 and Apple agreed to replace it. When the replacement came the signal was fine, but the battery was noticeably worse than on my original phone. The phone got hot when browising the web and sometimes lost more than 1% per minute. Apple agreed to replace the phone again, but this one is exactly the same. Lots of heat when charging and in use, often around the SIM card slot. I can't believe I have got two 'bad' ones, so am looking for ther possible reasons. I tried both phones as completely fresh installs as well as restoring my previous backups, so the only constant has been the SIM card. Is it possible that a faulty SIM could be causing this? I doubt my network will swap it out without a fee, so I want to be sure before I change it!