We went for the day when DS was 12 weeks old for feeding and day sleep help.
Leanne was amazing and helped a great deal. There is some crying involved with their techniques. For us it was in 2 minute increments which I was OK with given it worked really fast and I was encouraged to regularly comfort him. By the end of the day he had gone from 40 minute cat naps at every nap to us having to wake him after 2 1/2 hours! I don't know that I would be comfortable with more crying than that at that age, at 20 months it might be more easy to handle. Had it not worked so quickly, I don't think I could have tolerated him crying for long, certainly not for every nap over a period of days.
Whispers also helped with developing a loose routine for us.