So the billing in Feb was for Feb 5th through April 4th? If that's the case, someone needs to train your agents a little better to explain that. So the extra 19.54 was for 29 days of the difference for the new plan (2/5 through 3/4), then one more month of the difference for the new plan(3/4 through 4/4)? If that's the case, then I guess that makes sense. It's a strange way of doing it.
What will really help is when I get my first paper bill, so I can see just exactly what is going on. What I thought, which I thought just about anyone else would think, was that my bill generated on Feb 4th (after it was adjusted, as when it was first generated it was for my old plan amount, then it was updated) would be for one day of my old service (2/4) and the rest of the month (2/5 through 3/4) at the new rate, prorated.
So, just to make sure, I may see this $40 credit (which it turns out I didn't deserve) disappear because of my misunderstanding due to the reps not being able to explain this. It's nice to know that, due to my lack of ESP ability, I am the fool.
