Charging cable locked to car during cabin pre-heating

[EvanstonI3]

I didn't include any as it seemed so non-descript:

no release button/lever on it. That explains a lot.

 

[Yorkster]

I'm charging the car with OVO ChargeAnytime to get the best rates and there's a conflict between the OVO and BMW app so whilst the car fully charges by my departure time the OVO app doesn't support the climatisation option hence I activate the cabin heating to keep the wife happy

Got it, that makes sense.