Best answer by stephenrand
As this is your first post, welcome to the Pure Planet community! When you post here you are talking to your fellow customers, not directly to Pure Planet.
My first thought on reading this was that the likeliest explanation is that you have misread your meter. But if you hadn't given a meter reading for a long time, then maybe your usage has gone up over the months and now it's caught up with you. That's why Pure Planet send you an email each month to remind you to send in your meter reading!
Can you let us know your last three meter readings with their dates? That will help to give us some idea of what is happening