I did give in and call them today and their initial response was to tell me to just ignore all the letters but they will keep sending them. Also meant that I would keep getting the debt collection ones too.
Got through to customer support instead of billing/collections and got a similar response until I let them know it wasn't good enough. Gave them all the details and they said they would look in to it. Not convinced that will stop all the letters though.
My home is newly built and it took me a few weeks after moving in to get the new postcode put on Royal mails system. At the same time I registered to stop junk mail so no un-addressed letters come here. No mail forwarding from the old address as I still have access there. The tranquillity that comes from a new address and lack of crap mail should not be underestimated
Just typical that VM are the ones to break that.