i'm having ENORMOUS problems getting my wife's account properly credited. eight phone calls, two emails, and finally a complaint to my states public utility commission. no word yet, but i've heard you get your miles in short order once you contact the proper authorities.
in lieu of MCI try
http://www.onesuite.com/ 2.9 cents/minute, NO monthly fee, AND you do NOT have to switch current carriers. just be sure to get a calling plan with MCI that does NOT have a monthly fee.