I bought an iPhone 4S about a month ago from our local telecommunications company and I love it! However, I have noticed that on a few occasions the battery drained overnight. Not every night. But for the past two nights now, it drained completely. The night before last I made sure all my apps were closed. Last night I turned off 3G, cellular data (which I do not have anyway) closed all my apps and put the phone into airplane mode. The battery was at about 74%. This morning, eight hours later, the battery is completely drained. I have contacted the tele company but wondered if there was anything else I could try before returning the phone, which would be such a hassle! Any advice, please? I do not have this problem with my two iPads and two iPod touches.