Breast Pump Coverage (GHI)

I was told by a rep that I needed a note stating it was medically necessary and it would be covered. I could call back one month before my due date and they would tell me where to order it from.
So, I obtained the note from my OBGYN, called GHI today and was told I must FIRST purchase the pump on my own, then send in all receipts, notes, etc, and THEN they will determine if i need it or not.

Two very different stories. Anyone have any experience or advice?