the R9 280X is the same graphics card as the HD 7970, AMD just took it and rebadged it.
I heard it from various place, that loads of programs still see the card as the HD 79XX series card
So no, you did not got scammed
They use the same GPU, it could be that you have older drivers that don't recognise the new hardware ID. Try updating your AMD drivers and see what happens. Alternatively, have a look inside and see what it says on the GPU itself.