i'd be asking the previous owner for a refund ....
unless the frame number is only one digit out which may mean a dvla cock up (try and prove it)....
you could end up with a Q plate ....
or finally the frame could have been swapped, but why the logbook of the frame wasn't used is beyond me as it will make it harder to get the logbook transferred to it (so i believe) which again could mean you end up with a Q
John Wayne is my hero, he uses a sixgun, I use six hammers