I’ve raised this issue with Microsoft Support, but feel that I need to document it just in case other people are seeing the same thing (and don’t realise that they don't have to pay!).
For the past few months I’ve been experimenting with the Azure Virtual Machine trial – and dutifully setup Locally Redundant (non-geographically dispersed storage) for the VHD’s – and created the Virtual Machines in the same region (North Europe). And all was well.
Until last week.
Since then I have been billed for the bandwidth between the VM and the VHD storage – something which, as they are in the same region, that should not be occurring.
I’m still waiting on Azure Support to resolve the problem (and refund the charges that I’m still accruing – because they tell me they can’t suspend them – sounds fishy to me), but the most amusing / annoying thing was that the support agent concerned couldn't identify that they were both in the same region. Funny, when I login to the portal it seems easy enough.