I am sorry, but the lufthansa call center people are a bunch of clueless and totally inefficient people.
I called in to book my rail and fly and it took almost an hour to have the rail and fly booked because the agent on the other line could not comprehend that if I don't live in Stuttgart, and my flight leaves at 6am, I would need a train the night before

.
On top of that, while the agent confirmed that it would cost 58 Euros for a two way economy class ticket, I got charged 30 Euros more for reasons I don't understand.
Sorry to rant, but as bad as Deutsche Bahn might be, I would rather give them my money directly than having to book Rail and Fly ever again.