They knew I got the OLCI email and when I called the ticketing line in UK they could see that I had changed my flight, but it had not fully registered. Therefore the desk should have known that I had changed the ticket.

The desk told me the flight was full in all classes with zero no-shows. That was not true, because they eventually found me a seat.

But I do not really blame the individuals. Probably they were just dealing with it as they saw it. At the end I even thanked them.