Follow up to this story, is that NI said if they could reach the former owner and confirm it had been sold, they could "re-issue" the serial number.
They also said I would have to go through the exact same process when dealing with East West.
In the end I gave up as it being way to difficult and time consuming.
The dealer who sold it has agreed to a refund.
So a bit disappointing, but thems the breaks I guess