A member can add or modify requests at any time through MS by phone or email. Just use the regular number. MS can also make PS reservations but they will no longer do it by email. You will likely be better off calling 404-WDW-DINE though which you can do at a much broader time range than MS.
DVC no longer takes fax requests to the resorts directly.
The main MS number can make PS for you. Keep in mind they don't open until 9 so if it is a covetted one (CRT or holidays) I would pay for the call myself at 6:59am 407-WDW-DINE