Question Summary:
We did not ask them for the money nothing they gave it so would it be permissible to spend this money?

Question Detail:

salam
I was travelling to a country i booked my tickets etc and on the last min the flight got cancelled so from the airline they refund us double the amount of money for the ticket because it was their fault.
We did not ask them for the money nothing they gave it so would it  be permissible to spend this money?
Jazakallah

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatoh
The double refund by the airline is permissible. You were entitled to the original price of the ticket. The surplus is a bonus and gift from the airline.
And Allah knows best
Wassalam
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah