Originally Posted by giblet

I had a flight from BKK-AMS on KLM that I upgraded with miles. When I checked in, I gave them my Delta Skymiles number and asked them to credit the flight there. It was a pretty frantic check in because we had a dog so there was a lot of other paperwork flying around. When I went to take the return flight a few months ago I noticed that the miles had been credited to my KLM account instead, and I contacted them to transfer them to Delta. They said it wasn't possible, because even though I had added my Delta account, my KLM number was still on the ticket because we had used KLM miles to upgrade. They have acknowledged that I asked to credit the miles to Delta at check-in, but said there's nothing they can do because the miles are already in my KLM account.