As above, chassis number is missing. The hole in the carpet is supposed to be there, it should have a plastic flap on it that you lift up and the chassis number should be stamped into the metal where the corrosion now is.

You can see it in this video


My bet is that yours is a stolen car, rung with a different identity. Have a good check of other serial numbers, there should be one in the windscreen, either rivettied to the dash board or underneath the wipers, and another on the front slam panel.