When filing a complaint, you should be aware of whether your flight tickets were purchased as a group booking. Even if, for example, you bought the outbound and return flights in the same transaction, the purchase may sometimes still consist of two separate bookings.
When the authority receives your complaint, they will look at where the flight tickets were purchased. If the purchase was made directly with an airline, the tickets will generally be considered a group booking.
However, if the flight tickets were purchased through a ticket provider, it is most often not considered a group booking. This is because ticket providers typically assemble your trip by purchasing individual tickets from the airlines, which can be from the same airline or different airlines.
If you bought the flight tickets through a package travel provider, the authority will generally consider the tickets as a group booking. However, there may be certain exceptions, in which case you will be contacted.