No refunds for customers

I bought a charger for my Samsung Galaxy Tab P5100. They sold me a wrong charger. When I went back for an exchange, they told me that they do not have it in stock . I asked for a refund and they refused to give me my money back saying I should wait until they have it in stock. Whats worse is that they don't even know when that will be.. They refuse to give me what I went there to buy but also refused to give me my money back so that I can go and look for it somewhere else. I don't know if I should sue and lay a complaint with consumer tribunal or not. But as things stands, I'm loosing money and business because of this.