Gatimaan Express: Raftaar meri Pehchaan - Sajid Akhtar

I had traveled from raipur to chennai on 07.08.2013, actually i booked IInd AC but after boarding in to the train i came to know the seat allotted me in third AC then i i traveled in third AC. TTR issued " certificate of permission to travel " to me to get refund amount for two tier AC to three AC. Now How i can file my TDR ? which reason i have to select in TDR file ? What the time permit for file TDR ? or any other option available and whats the time permit?
Please any one clarify

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