Typically, I called VM at 5.30pm to tell them they had routing issues (having already run a trace route locally when I couldn't get to the US websites) but sadly, I got the Indian support team. They helpfully told me they had no record of any issues and that I needed to "clear my cache". When I tried to explain that really wouldn't help, they cut me off!
I called again later, maybe 8pm and got hold of UK support (HOORAY!). They were much more helpful and acknowledged the error as well as taking details from me regarding the trace route. By this time they had already started investigating the cause, but had no lead time for solution.
Good old VM!
Now all they need is to sort out the issues with downstream utilisation which has meant I've had much, much less than the 20mb I pay for SINCE FEBRUARY!