It's very easy to leap to conclusions; the OP says that (s)he was in the zoo for five minutes before confronting the management to make accusations. I'm not surprised the director didn't want to talk - if someone from another country came to my place of work and five minutes later was making threats and accusations, I think I might be similarly recalcitrant.
The Colombo Zoo may be very poor; the pictures posted do suggest that it is not great, even if the description above of it as a "hell on earth" may be somewhat hyperbolic. But the reasons for this may be complex and deep-rooted, and I would be surprised if the zoo's management was not aware of the place's shortcomings. I'm not sure that restating this fact is the way to bring about improvement.
Constructive help is always better than criticism. And while I have no idea of the OP's cultural background, I do think that those of us who live in the west need to be very wary of marching in and passing judgement on what happens in a country such as Sri Lanka. I appreciate that many will - wholly justifiably - disagree with this, and will argue that there are some absolutes that transcend national boundaries. My point would be, though, that change will be more likely if a collaborative, non-judgemental approach is taken, rather than a confrontational declaration of war. I would also suggest that there is a big difference between a place like this and some of the wholly commercial places to be found in, for example, Thailand, in which people are using animals to get rich - boxing orang utans, photo opportunities with drugged tiger cubs and so on.
