Keeping track of my own Bandwidth Usage

[#1]

Living in a house with a teenager on an Xbox and a 9-year old who loves Youtube, I found myself constantly checking the VMBU to make sure we're not going over quota.  Now that I've moved over from the old Premier Broadband service (13Gb quota) to Plusnet Fibre (120Gb quota) we've got more bandwidth to play with but we still have to keep an eye on things.  Especially when my son decides he wants to install World of Warcraft (10GB download) and doesn't tell me until he's halfway through!
So I made myself up a handy spreadsheet in Excel, with graphs and everything. All I do is put down the daily figures for Allowance and Overnight from the VMBU and the spreadsheet does the rest.  I've got colums that show how far above or below my daily allowance I am for each day (120Gb a month works out about 3.87Gb a day).  or how far cumulatively I'm above or below my expected quota as we move through the month (in other words how much I've got to spare, or if we've got to pull our horns in).
And then of course there's some graphs showing daily peak and overnight usage, average daily and overnight usage, and cumulative daily and overnight usage.  Expected quota usage is shown by a green line in the last two, so I can easily see how far under (or over) quota I am.  I've found it very handy, so if anyone else would like a copy, here's a zip file. 
http://www.spacewarp.co.uk/ISPUSAGE.ZIP
There's two versions in there - "NEW" is in Excel 2007/2010 format while "OLD" is in Excel XP/2003 format, plus a README file.  There's already some data in there so you can see how it works, and you should be able to change it to suit your own Allowance level. Please read the README file, and any comments are more than welcome. 
There are no viruses embedded in either of these files, but you should always scan any zip file you download from the internet.

Dave

[#2]

That's a jolly good idea Dave that some people will find very useful, but there is one thing you need to correct and that is the ratio of Kb to Mb to Gb is 1000 with Plusnet as detailed in the RH column of the VMBU main page. Plusnet aren't the only ones I'm afraid that have this stupid factor. Bits are BINARY and so it ought always to be 1024. IIRC this stupid and IMHO incorrect method was started by some Hard Drive manufacturers many many moons ago so it made it appear that their drives were bigger with more Gb 
But your idea has given an excellent brain wave, that I will now present to Plusnet.
OK, Plusnet how about being able to download our usage breakdown for each of the last 3 months and the current month as csv files in a similar manner to that available for phone call data? Pretty please.

[#3]

Thanks for the comment, Brightspark.  Yeah, I'd forgotten about PN's use of the Mb to Kb conversion. That's a consequence of me working in IT support!  It also explains why my usage is always slightly off at the end of the month, presumably depending on how many times I input figures in MB.  So if every day I go over 1GB my figures will be accurate!  
Of course with KB it doesn't much difference and TBH I could just put zero on a day when I do less than a Meg, but then I'm in IT support...which is why I'm obsessive about numbers!
You're absolutely right, and I have now changed the README file and the test data in the two spreadsheets to reflect this (plus a couple of other cosmetic modifications).  If you have already downloaded them, please do so again.
Dave

[#4]

Sorry, screwed up on the last update. Missed out the README.
All back now.
Dave