I do hope you get your miles. My wife and I tried the same thing last year. It happened just the way you described. Very easy. However, MCI reps just tell you what you want to hear.
Six months later and no miles, we kinda got concerned. Gave them a call and they said "Oh, there seems to be a problem. I have fixed it." Wrong.
We are now with ATT. I probably would have stayed with MCI, but they make promises that they cannot keep.