Indian Railway
Berth is not alloted as per ticket

I had booked a ticket from rourklea to bangalore on 29-10 by TATA Yeswantpur. I booked for three members. I got the berth and coach because it was confirmed tickets. I cancelled one of the members berth which was lower. Other two berths were side upper and side lower. But i could not understand that how the my side lower berth got cancelled but i cancelled the lower berth only. I was travelling with my kid and i wanted lower berth for my kid's conveniance. TT is not able to answers and he suggested me to register a complain against IRCTC.

please help me on this...