Potential wrong Gas meter number (not reading)

Hi, I have received a ridiculously high gas bill and i have barely had the gas, not enough for £100 worth considering we have been using an electric heater in one room and no radiators on at all (I know cold) just because our last bill was near £90.
Obviously wouldn’t of checked this over summer as that’s when we moved in.
I have now checked the gas meter, leaving the hot tap on and watching the clock move on a different meter that isn’t ours.
So how do i go about getting this rectified or even checked properly?

This is something you need to speak to Bulb about come Monday. (closed weekend)