Best answer by Duppy
Welcome to the community.
When you post here you are talking to fellow customers not to Pure Planet, but we are willing to help.
When you get a reminder email it gives a date by which to submit your readings, if you submit on this date you will not get estimated readings.
Pure Planet have no way of knowing that the property is unoccupied, and will base estimates on the figures you gave when you initiated the switch to PP, and if you want to stop estimated readings you can either submit your readings on the date specified or contact PP via Wattbot and inform them that the consumption is low due to being empty.
Your account is updated each time you submit your readings