The person who was based in India said that to give the information requested would be breaching Data Protection so I am no further forward.
What a load of rubbish. How can it be breaching the Data Protection Act. It is you who is making the request about what information they hold about you and your usage of the Internet. You may have to request it in writing and pay to get the information but they would have to provide it if it is available.
So basically devices such as I Phones I Pads X Box 1 etc will all take maximum advantage of the download speed available thereby increasing usage ?
That is correct. Instead of standard quality video, it wiil select HD video on things like Youtube and iPlayer.
If you have than many devices in use, especially if you stream video, or do gaming, you will soon use up 40Gb.
If you upgrade in the same month as your excess usage, BT normally do not charge for that excess.
Keep a watch on the broadband monitor, on a daily basis, to see what you are using. Remember uploads and dowloads count.
If you are on a discounted deal, you may find that the amount of the discount, is applied to the upgrade price, for the remainder of your contract.