Had a reservation on an SAS flight, codeshare with bmi, booked through bmi.
Called to ask SAS if I could bring the flight forward 24hrs as my business had concluded a day early: after checking they said "no" it's a bmi codeshare check with them.
Checked with bmi and they said, "yes you can change but it's going to cost you lots". Natch I declined.
When I gets to check in SAS in ARL tell me that I don't have a reservation: long and short of it is they had cancelled my reservation without telling me when I made the enquiry: not happy!