I think the hallway lights or another flat are wired into my electricity meter. What can I do?Beta*

Signs include bills that are far too high, or your meter still running when everything in your flat is switched off. Test it by turning off your main switch and watching whether the meter stops. If it keeps going, or communal lights go off when your power is off, the supply is likely shared. Tell the landlord in writing and ask for an electrician to check and separate the supply. You can also contact your energy supplier and ask for a meter accuracy check. If you have been paying for someone else's electricity, you can claim the cost back from the landlord.

Sources: Citizens Advice: if you think your meter is faulty