Indeed, look you would be entirely wasting your time trying to get any fix from VM for this, you need to get onto your current, existing provider and register a complete loss of service and get them to deal with it. If they discover that VM were responsible then they can take it up with them for recompense, and they'll certainly have better lawyers to throw into the mix - either way, not your problem!
One possible fly in the ointment would be if you have already put in a cancellation request with your existing provider, now although in theory you are still a customer and as such are entitled to equal treatment to everyone else, in practice, they are very likely to acknowledge your issue but see that you are leaving soon, the temptation will be, not unsurprising really, to 'downgrade' the urgency of fixing your issue on the ground of 'well what will you do, leave? Oh no wait!'