My iPhone always turns off when it's cold (From 0 C to -15 C) no matter how much battery it has. I know that there are some defective models and mine is actually one of them and I'm eligible to get a free battery replacement but don't know if it's from the battery. The service is also far away from me so I will have to send it through a carrier and wait 2-3 weeks. These turn offs get so annoying over time. So should I send it to get a replacement?