In March 2019, I booked my 13 yr old a flight on Iberia website to go to from Toulouse to Chicago return for June/July 2019. Their website has an option to choose Adult - 12+, Child 2-11 or Infant Under 2. Since my daughter is 13, I choose the adult option and the dates of travel. A list of flights was provided. I chose the best flights based on times/journey (i.e. least amount of layover time). The outbound flight was on Iberia and the inbound flight I selected was with BA, a partner of Iberia (and also owned by the same parent company). I entered in all of the required information and the booking was paid for and confirmed. I had made almost the exact same booking 2 years ago for my other daughter who was 13 at the time and felt confident that the system was valid. A few days before she was due to travel, I checked the website to see if any more information was needed, and if an authorisation form would be required in Spain as she has a layover there (kids travelling in France are supposed to carry an official authorisation form). I noted that the section for unaccompanied children stated that their partners carriers have different rules. I checked BA's website and found that they don't allow 13 year olds to travel unaccompanied at all! I also checked on the internet to see if anyone else had this problem - and low and behold I found a post on this website of the same issue and the child was refused at the check-in the return flight -- thus leaving the child stranded without a means to get back home! This made me extremely stressed and I immediately called Iberia to explain the issue -- and was told there was an option to change the return flight to Iberia with the same date of travel, but a different time. I agreed to this change and then was told I had to pay the fee to change the flight, which came to 482 euros. This was more than I paid for the original fare total (outbound & inbound). When I inquired further on the fee, I was told it included a penalty charge of 180 euros for changing, plus a service cost and flight cost. I explained that I did not agree that I should be penalised for this and asked to speak to a manager. The conversation got nowhere, and in the end was told there was no way they would change the flight if I didn't pay the fee. Of course, I paid it, but I am planning on seeking a refund for the penalty and original return flight cost, as it should not have been an option for this booking. My argument is that their online booking system is at fault and should be modified to show an option for Young Adults (12 - 15), and only airlines that will carry them be listed as options for booking. It is irresponsible to refuse minors to check-in on flights that have confirmed bookings - it could leave minors at risk of being stranded in foreign countries.