sill: rocker panel or threshold plate?

Dear Triumph list,
I also own a Volvo P1800 and I also subscribe to a P1800 listserv.  A guy on
that list said he had 'sills' for the p1800 to sell.  I ordered one and but
was suprised when it came as it was a door threshold plate and not the 'rocker
panel' like I thought.  Who's at fault in this transaction?  Me or him?

Thanks,
Paul Dorsey