let me to this and the author says it's the actual conversation:

Swigert: 'Okay, Houston, we've had a problem here.'
Houston: 'This is Houston. Say again please.'
Lovell: 'Houston, we've had a problem. We've had a main B bus undervolt.'

Very very different than what I would have said had I been on board, which would have been more like:

"WE'RE GOING TO DIE.... IT'S OVER, TURN OUT THE LIGHT... IT'S ALL FRED HAISE'S FAULT.... I DIDN'T TOUCH ANYTHING"