I am curious as to your fare basis for the P fare. I'm not trying to berate you for buying an upgradable coach fare. What I'm trying to propose is that if no one from DL is willing to play ball and let's say you have a YUP fare, see if they could rebook you in that full Y fare and then just have you immediately upgraded back into F? Obviously that won't work if you have one of the H/S/M/B...../WNUP, but it's worth a shot to ask?