It would be really useful to have a breakdown of how much usage has been allocated to which device for the current month, e.g.
iPhone 6.4 Gb
Android Tablet 2.3 Gb
Family laptop 1.2 Gb
Wii 0.3 Gb
This would help identify which member of the household was putting us in danger of exceeding our limit each month! It could also be used to see if any device were sending or receiving a lot of data without us realising it.
Software to do this is available for download, but I don't think it is compatible with a BT router.