How do I know that I am getting Shell V-Power when I see non-Shell trucks at Shell stations?

I use Shell V-Power (premium). I thought it was only Shell trucks that fill Shell gas stations..How come I sometimes see "Klemm" or "Pac" tanker trucks filling the tanks there? Should I assume that some Shell gas stations are ripping me off and that im not getting my V-Power that I supposedly think im paying for?