Hey guys help me out with my xbox 360 controller issue?

first it started like this my controller's left trigger was not working and then i called microsoft and he told that he will send me a replacement if i send him the date of purchase of the bill . but actually i brought it from a local person who was not a very big retailer and he didn't give any bills but only gave recipt but even that is missing now and when i asked the retailer he said he cant give another recipt he is a dumb though doesn't knows anything about the 360 and also my console is less than 1 year but what can i do to get a new controller please hlp me.......... i am really frustrated