On 16th August at 8.51pm I bought 500MB data. My balance went from €28.03 to €23.04 for the €4.99 charge. Since then I have sent 3 texts charged at €0.15 each. I still have 131.7MB data remaining. I have made no voice calls. However my balance is now €14.07 when I estimate it should be €22.59. Why is this?