Hey.. I recently bought a second hand (but nearly new) iPhone 7 32GB, upgrading from an iPhone 6 Plus. TouchID on my iPhone 6 always worked great apart from if I had slightly wet fingers (which seemed to confuse the TouchID reader) and indeed my other iPhone (an SE) also works fine. However this iPhone 7 is a different story entirely, and it's starting to drive me crazy. I've enrolled just one finger (my thumb) and at random times throughout the day, when I try to unlock the device, it simply will not unlock using this digit. I can try multiple times, with my thumb in all kinds of angles and positions, and it just tells me it didn't recognise it - but if I unlock the phone with my PIN, then lock it again and try unlocking with TouchID it'll work fine. I can then lock / unlock using TouchID as many times as I like. However, I leave the phone for a while, try and unlock with TouchID and the problem returns again. It's extremely irritating! I'd happily take it into an Apple store to show the problem to them, but the issue is the consistency of the fault... as it might work sometimes, and might not other times. It's entirely unpredictable in terms of when it won't work. I've checked the TouchID sensor is completely clean / free from any dirt and my hands are clean. Does anyone know if the Apple store are likely to be willing to swap out the handset or do you think they'll need to see evidence of the problem occurring? Thanks.