Decline of Policy because I'm Bipolar

So last week I app**** for Lie Cover, all seemed to go well. They sent a lady to draw blood and I gave her all my application forms. I'm bipolar so I had to state that on my forms. They said be as honest as possible and I did. I was hospitalised for my Bipolar a month ago and had my meds sorted out. I got an email on Thursday stating my Life Cover was declined. They are not telling me why but I had to fill in a form in order to get my doctor to tell me why. Firstly why can they not tell me as its my policy. Secondly why can they decline me for being Bipolar, I find this a bit unfair. Bipolar is just a disease, so why am I being declined? I find this really unfair!!! I have medical aid with Discovery, I have insurance with Discovery, as well as Vitality.... should I move all those because I feel like I am being discriminated against!!!