Originally Posted by
davetravels
If the seat map is mostly full this far in advance, and you had a schedule change today, the seat map is probably locked until the computer is finished with its updates which happen on Saturdays.
The OP may be suffering from DL assigning different configurations of 757-200. If he paid for Comfort+, he'll get Comfort + or a refund. It may not be the specific Comfort + he wants.