I was travelling in the US from Canada. I took care to turn off roaming, data, and even had it on airplane mode unless connected to a WiFi spot. Even so, on the second day I received a message that I had run up a 30$ Bill for data usage. I may have checked one website for an address, but otherwise nothing else. Surely that did not cost me 30$ in data!! How can I see where the cost is coming from? Does my data usage determine if I am using WiFi or data from my plan?