TLDR: I was denied flying because of a rule that never existed, then forcefully rebooked 4 days later, and the customer service is unreachable. Longer story: I was attempting to return to Zürich from San Jose. Because of the Covid, for that I needed a PCR test 72 hours prior to arriving to Amsterdam. Half a day prior to the flight they notified me that I also need a max 4 hour old antigene test prior boarding. I called them, they had no idea how is it possible to geet such a test for 7:45am when my flight was. I managed to do it at the end, and had every paper ready for boarding. The online checking was disabled because of government regulations. When I tried checking in, they denied me because I was in Costa Rica just for 13 days, and Europe has a rule that if somebody leaves Europe, he should stay there at least 14 days, and cannot return earlier. Yes, this is ridiculous. We called the consulate, he checked it and such rule never existed. After calling some head of whatever and discussing for ~40 minutes, they forcefully rebooked my to a flight 4 days later, but my visa for Costa Rica expires tomorrow, so I will have to stay in the country illegally. Not to mention that I have to redo all the covid test which costs around $200. For the question of how on earth is 13+4 days 14, and why don't they rebook me for tomorrow then, they were not giving an answer. I tried calling KLM but they don't have a 24/7 hotline and it was offline. I'm still trying to contact them but the phone hotline disconnects saying that the waiting time is >30 minutes. On the chat they won't respond. I will never ever fly with them again and am considering contacting a lawyer.