My parents tried to quit smoking by themselves, but it didnt work out, so I told them a story about a brother at my church. I will tell you the story as well, and hopefully it will give you some insight.
Him and his wife were both big time alcoholics, and neither of them had God in their life. One day his father died, and while they were getting ready for the funeral, his son was getting the car all ready in the field, and while he was backing down the driveway he ran over his little sister (the brothers), then two day's later his brother or brother-in-law had drowned and passed away. So they all left to go visit his family in another Provence to tell them what had happened. One morning, he realized that there was more in this world than us and he prayed to God, and asked him to take away his addiction and he would live his life for God, with dedication, and neither him nor his wife have craved a drop of alcohol since.
I told my parents this story, and said "have you prayed for God to take away your addiction? Because he can, and he will."
So that night my mom prayed, and she hasn't craved, wanted or smoked a cigarette in a month. My step-dad has had 4 in three weeks, just out of habit, but didn't really want them.
So what I'm trying to get at is, to just ask God to help you with it, whatever it may be, and just have COMPLETE faith in him, don't wonder when, or how, or anything else, say to him:
"God I know you can take my addiction away. Please take my addiction away and I will do anything for you."
or something along those lines. I know that God can cure you, Anything and Everything is possible with God. All you have to do is believe and put your trust and faith into him.
In the meantime, I shall pray for God to take away your addiction, and when you are rid of your addiction please tell us.
God Bless Brother.