poor service Samsung

My wife upgraded her MTN contract 2 months ago with a new Samsung cell phone. The deal was done telephonically and the phone delivered to her. Now 2 months later her microphone stopped working. NTN said they need paperwork to send the ohone to Samsung for repairs. Paperwork was promised via email when her phone was delivered, but they never sent it. Surely Samsung can tell via the phones serial number that it is only 2 months old?? Also, the model has only been available for 4 months SO it is IMPOSSIBLE for it to be OUTSIDE the warrantee period?! Samsung, your reputation is at stake...SURELY YOU SHOULD HONOUR THE WARANTEE on a phone 2 months old? The serial number will prove this! Derek 08277****5