I had two BE class award tix to LGW and had to cancel one. Canceled on 1 Oct, flew on 10 Oct and the miles finally got redeposited on 19 Nov. Must be a new record!
Seems the original person I spoke to on 1 Oct had used the same ticket number for the canceled tix as the one I flew on. After I called the Medallion Desk on 18 Nov, the agent got it straightened it out and the miles showed up the next day. Of course I had three emails to DL.com with no success and who eventually told me they would forward it to the Medallion Desk.
Cheers