I am being charged for extra data despite my cellular data being off and my hardly using the network, twice the new data message has arrived at a similar time when phonenis not in-use; phone is reporting 300mb used on this occasion. I will not pay and end service if this continues.
Reset your phones internal data meter.
If its android you can set warning and cut off limits. If its iPhone then just set the data counter back to zero. Then if you get a warning (or even just check the counter every day) you will be able to see if the phone agrees it has downloaded data or not.