I recently had a customer who started smoking again within a few hours of hypnosis. When this happens there is generally one of two things happening:
There is a part of the subconscious brain that does not want to let go of smoking. When this happens it is fairly easy to correct by a process called reframing.
The person did not want to give up. When I rang this particular customer to come back for a reframing session she refused to come back. After talking to her for a while she admitted that she did not want to quit smoking and had only come to me to please her partner. Despite being asked several times at the hypnosis session if she wanted to quit smoking she still insisted that she did.
The need to please her partner was so strong that it overode everything and she was dishonest with herself and deluded herself that she really wanted to quit smoking. I say this time and time again you have to want to quit smoking. Want to needs to be more than need to. Without the want the process and by the way any process to quit smoking will not work.
Be honest with yourself and really make sure that you want to quit smoking, if you do not all you will get is frustration about the fact that you could not quit.