I have found hypnotherapy useful for coping with stress caused by having IC and would recommend it but choose yr hypnotherapist carefully - I got a recommendation for someone I trusted.

Just happened to come across this article in a mag about how hypnotherapy could help frequency problems:

"Hypnotherapy can help lessen the feeling that you need to urinate and get rid of any stress contributing to tension in the body. If your bladder is not full but you feel the urge to urinate, do this: imagine this feeling as a colour, bring it outside your body, give it shape, then a background colour that is opposite to that feeling. Fade this shape into the background until just an outline of it is left. Shrink this down to a dot, then imagine rubbing it out or blowing it away so that all you have left is the background colour to free you from the urge. Hypnosis can also reset the unconscious to minimise the frequency with which you feel the need to urinate and give you tools to cope with stress".