This happened:

To make things really interesting, my booking was a somewhat complicated one for a flight out of ARN and the cheapest price was, of course, in SEK and the EUR price was about 10% higher.

First thing I tried was book online and choose Sweden as my country. Error message, but luckily a booking with a PNR appeared in my profile. I noticed this only later.

Then I called the Premier line, which was totally useless. They gave me a Finnish number to call. This number was answered in English and the helpful agent started to construct my itinerary flight by flight. According to her, there was no availability in the requested booking class on one of my flights. No matter what she tried, nothing worked. At the same time, I checked ITA Matrix and there was availability for up to 6 people, same on united.com. I already agreed to change my departure airport to OSL, but there were some problems with this too.

However, luckily I checked my profile and noticed the PNR for the "error message reservation". I gave the agent this PNR and she was able to start finalizing the reservation. Some problems followed, but eventually I was able to pay the SEK price in EUR, which was fantastic, because I saved the 10% price difference between the Swedish price and Euro price and saved 2% for not having to pay in a foreign currency.

Total time spent on the phone: 30min with Premier line, 60min with "Finnish" number - totally worth it for the feeling of satisfaction when you are told numerous times that there is no availability in your desired booking class and finally you can prove that there is