I got them to do this for my girlfriend from a nobody --> Silver when her next two segments put her over 25K. They verified the itinerary and mileage, made a remark that she would just be making it (25,057 miles -- duh, why do you think we went thru EWR?), and granted it to her.

Bottom line is it might be worth a shot. Call during the business day, though. The night shift folks can't do this kind of stuff.