S2340M, yogore staining

So I've apparently gotten a "Yogore stain" from my S2340M Monitor. I'm now aware that I cannot get the monitor fixed so I wish to have it replaced. The device was manufactured in March of 2013 and I received it at June of 2013 so it should still be under warranty since monitors have a 3-year warranty. The biggest problem being that Dell won't recognize the Service Tag which is 0293M3 and the auto detect won't work at all.  How do I send the thing back to Dell for a replacement if the service tag can't be recognized? This problem seems to be a very common problem suddenly among Dell Monitor user. (Pink tint with horizontal lines).