Smart meter is going crazy, boiler issue?

I moved to a new flat and my meter is not working ok I think. It's not detecting my boiler when I set it up at night and for few days in a row have over 1.5 kwh when we are either asleep or out . Can't understand where is my boiler at night and what is causing the other usage- 1.5kwh per 30 min. Nothing in the flat is using that apart from the boiler, oven or dryer but I haven't used them at those hours at all. For reference I can say I moved from another flat in the same building so my boiler is the same so are my appliances. I checked the clock at the boiler timer and it's correct   the meter clock is also correct.  The boiler is having its light on at night when its set up for heating.  In the morning it shows 0 usage or very little and it's 3kw boiler