To do something you didn't ask for Idiom

[Chazz]

Hi,

I am looking for an idiom that carries that meaning.

For example: the airliner changed my flight on their own initiative? Account? Accord? Any other suggestions?

Thanks

 

[SwissPete]

Do you mean

The airline (not airliner) changed my flight without asking/notifying me.​

 

[lingobingo]

Or, in this case, without my permission – colloquially, without my say-so.

 

[Gorgiewave]

The airline changed my flight without so much as a by-your-leave.

 

[Gang-Gang]

The airline made the unilateral decision to change my flight.
Unilateral in this context means that one of the two parties involved in this event acted without consulting the other party. In this example, the airline acted without consulting you.