Indian Railways — I'm complaining about allocating my seat to unreserved passenger

I have been traveling from naharlagun to guwahati and my berth was s6-46 but since my friends were in berth s6-58 so i was with the till 11 and in between the tte came and he marked my berth 46 too after i showed him my ticket. But after 11 when i went back to my seat the seat was allotted to someone and she argued telling it's her seat and the tte has alloted her the seat and she even paid for it. The tte was clearly aware that the passenger of berth 46 was boarding the train but still he alloted that seat to others and i had to travel the whole night journey without seat. This is a very bad thing. The tte shouldn't allot the seat to others this way when he even ticked my ticket and knew that i was on the train. This should not happen and i hope the indian railways look upon the problem