I never thought I would use CC but at 10 months with DD still waking for a BF every 3-4 hours, I was at my wits end. Within 3 relatively easy nights, she was sleeping through and has ever since. I was converted - lol.
Basically, what we did was set a 20 minute routine. We'd put DD down like normal, she'd fall asleep, then wake at 3-4 hours. At that point, we would go in, settle her, she would wake within a few minutes and cry. We'd let her go for 20 minutes, then go in and settle her, and again, if she cried, let her go for 20 minutes (and so on).
The first night, she cried 3 times, the 2nd night, 1 and a bit times, the third night, she whinged for a short period then slept through.
Not sure if that will help. My advice is to pick the routine you want, and stick to it. It is a battle of wills, so if you cave, the efforts before would have been a waste of time. You want it to be as quick as possible so as to reduce the stress on your bub.
Good luck !
DD is 3yr 8 months - DS is 6 months