I just started having this issue. I usually have data roll over however last month my data ran out, and this month I have already used half of my data with 20 days left to go. I check my data utilization and it shows me using .5-.8 GB each night while I am sleeping with my phone on sleep mode (which has been a setting I have used for months). I am connected to my wifi. The other phone on the account is not having this problem. What are you doing differently.
Nattyland, we are sorry to hear that something is unexpectedly using your data. As you have indicated that the other line is not experiencing this, it honestly is unlikely that this is anything that we are doing but rather that something installed on he actual phone is doing. Do you recall adding any new apps, games or software recently? Which make and model phone do you have?