KLM Royal Dutch Airlines review: Flights

I am writing to raise a formal complaint regarding a serious failure with a booking I made with KLM, which resulted in my friends being unable to travel as planned, despite receiving confirmation from your airline.
On 9 January 2026, I booked two flights with KLM for travel from London to San José, Costa Rica, scheduled for 26 May 2026, under booking reference ZVCX8D. Following this, I received an email clearly headed “BOOKING CONFIRMED – London to San José”, which I relied upon as confirmation that the flights were secured. I shared this confirmation with my friends, and we proceeded entirely on that basis.
This was a particularly significant trip, as it represented a long-standing, once-in-a-lifetime ambition for one of my friends, who is living with progressive Multiple Sclerosis. The planning, cost, and emotional significance of this journey were therefore considerable.
In the lead-up to departure, I experienced difficulty accessing your system to check in online. However, I understood from your guidance that, in such circumstances, passengers could attend the airport and check in at the KLM desk. At no point did I receive any communication indicating there was an issue with the booking.
However, upon arrival at the airport on 26 May 2026, your staff informed us that although the passengers appeared on your system, they were not ticketed and therefore not booked onto the flight. This was completely unexpected and contradictory to the confirmation I had received.
This situation was extremely distressing. It was made even more concerning by the fact that:

Your staff confirmed that seats were available on the flight
However, my friends were only offered travel if they purchased new tickets at approximately three times the original cost
There had been no prior communication from KLM to alert me to any issue with the booking
We had already incurred additional costs, including pre-booked accommodation and car hire, in reliance on the confirmed booking
I have since become aware that other customers appear to have experienced similar issues, raising serious concerns regarding your booking and ticketing processes

Given these circumstances, I consider that:

I was provided with misleading confirmation that the booking was complete
KLM failed to ensure tickets were properly issued
No opportunity was provided to resolve the issue prior to arrival at the airport
The handling of the situation at the airport was unreasonable, particularly given that seats were available

As a result, I am seeking:

A full and detailed explanation of how this failure occurred
A full refund of the original booking
Reimbursement of all additional costs incurred, including accommodation and car hire
Appropriate compensation for the distress, inconvenience, and significant personal impact, particularly in light of my friend’s health condition

I would expect this complaint to be treated with urgency and seriousness. Please provide a full written response within 14 days.
I am willing to provide supporting documentation, including the booking confirmation email and receipts.