Yeah, overnights usually do not work out in the online system. Only way is to call. If would try to push them to waive the phone service fee since it is their fault their booking engine is so crappy and you had to call. These would be the words I would use... maybe a bit less offensive

Call during European business hours the Swedish number. Those are, form my experience, the most helpful and empowered agents. Best time is between 10am and 12pm or 2pm to 4pm. Avoid European morning, lunchtime and after 4pm.