A peculiar e-mail!

[#1]

I have received an e-mail from Plusnet, saying that I have almost used up all my month's 15GB (BYW2) allowance. It warned me of all the dire consequencies which will happen if I do exceed it. 
However, it's the last day of my Broadband Month (new month tomorrow) and I still have two and three quarters gigabytes of my allowance left.
Very strange!
I wonder if anyone else has received an "early warning" like this?
Notification of only a few hundred KB left, I can understand, but not 2 3/4 GB.
From a puzzled
Keith

[#2]

It's a very simple automatic procedure that triggres the mail when you reach a certain percentage of your monthly usage allowance. There is no complex analyis of how your usage is spread throughout the month.
The system is in place as an aid to avoiding people going over their usage allowance without noticing. Just ignore the mail if you aren't in danger of exceeding your allownce.

[#3]

You'll get that email warning at 80% to advise you that you are approaching your allowance. So on a 15GB product that'll be at 12GB.
If we left it till a few 100k left then you could easily use that in a very short space of time before the email actually arrives.
Hope that helps explain.

[#4]

Thanks for the very prompt replies, both.
Thanks also for the explanation. All is now clear
Keith