It’s possible that other businesses also have their meters in your premises (perhaps because the walls are in different places now than they used to be). Ot there might be old meters that aren’t used anymore. The trick is to look for the MPAN on your bill, and then find the same number on your meter. (You might want to label your meter so it’s easier to find next time.)

If you aren't sure which are your meters, get in touch.