The first is grammatically correct but sounds weird to me. The second one is how I would say it. The third one is incorrect.

Why have you made this decision? - present perfect. You're asking about someone's decision now. Why did you make this decision? - past simple. You're asking about someone's decision in the past (ie. it doesn't affect the present). Why did you have made this decision? - is broken English and makes no sense. However, "Why did you have this decision made?" is asking about a decision now, but the person being asked only authorised the decision and didn't actually go through a process of choosing. Still, it's a very strange construction.

I think the second one is correct ,but i m not sure about the first and third ones.