Well...............I had a telephone conversation with DVLA complaints department.
She looked into my case and admits she should not have sent that letter to my MP, as my application was still being dealt with by "another department", which she did not know about.
I told her my previous 4 registrations had all been given different styles of VIN numbers, despite all having the same YYMM####R VIN number plate. It seems the USA knows the cars as 74/####R,, and the last car which took 8 months, was a Canadian export car with less identification plates, which confuses them.
She gave me the details of the very helpful lady with the musical Welsh accent, who will deal with my next 2 applications to prevent the same thing happening again. At least they admit their mistakes.