Deepak, I'm sorry about your phone. However, you banged it up against something. It is not as if you just touched it with your finger and the metal caved in.
Please, let us be realistic. Too many times people damage their phones when handling them and then try and make it out to be a defect. It does not hold up. Was your phone designed to be "hit against the wall and my table's leg" as a normal use scenario? I believe not. Is it engineered and tested to withstand some forces that might normally occur? Yes. Did you exceed those forces? Obviously you must have.
Will other users of the phone read your post and try to "hit their phone against the wall and a table's leg" to try and see how much or how little force you must have used to whack your phone to cause the dents? Not a chance.
What is your goal here? Sympathy? I feel bad your device got damaged. Validation? Nope. You bang your phone against stuff you take the consequences. A refund or free repair? We have no control over that. A warning to 830 users about a "defect" in the phone? Damage due to accidental handling is not a defect, it is a consequence. Sometimes stuff happens, dude.
Again, I'm sorry your phone got dented...