I called Verizon because we have been going over our data the last 2 months. We usually carry over. Out of our four phones, it was my husband's that suddenly spiked and he is the third least user of data. He is almost always in wifi and hardly uses his phone. After reviewing the data usage on our account, we saw HUGE (like 30% of a GB) used in the middle of the night or while he is in secure wifi at work and and not using his phone. Verizon offer no real help just to make some adjustments in the settings that do not account for this crazy use of data.
We temporarily went to unlimited until we either get some answers or more probably switch to T-Mobile.