For clarification, the term “free” means that you will not be charged the fare — including taxes, other non-optional charges, and a small cabin bag with a maximum of 42 x 32 x 25 centimeters — for the free seat; but you will pay an administration fee for each free seat as well as for each paid seat.
For example: if you book two seats, you would pay the flight price of one seat and the administration fee for two passengers per flight. This means that if the price of the flight is ten Euro for one passenger and you book seats for two passengers, you would pay ten Euro — 20 Euro minus ten Euro for the second free seat — for the two seats plus twice the administration fee for two passengers. If the administration fee is eight Euro, then your total cost for airfare for you and the second passenger would be 26 Euro.
Of course, this promotion does not apply if you book only one seat; and the number of seats available at any particular price is limited. The seats purchased must be used together and cannot be cancelled or changed separately.
Large cabin bags and each piece of checked-in baggage are subject to additional fees; as are any other optional additional services and products — including but not limited to a large cabin bag, checking in for your flight at the airport, insurance, car rental as several examples — you must pay for them, as they are not part of the promotion. This condition applies even if they are purchased in connection with a free seat.
Fees also apply for any changes initiated by you to your completed reservation; and if you change flights where the new total airfare would be lower than what you originally paid, you will not be entitled to a refund except for the amount of the lower taxes and charges.