Indian Railways — Ticket booking & seat allotment

I have booked 2 tickets in 2ac class in train no. 04501 date 23rd may2017, travel station lko to cdg.
At the time of reservation our pnr status was rac but on 23rd we got message seat confirmed in 2ac birth no.*& *.
Bt after chart prepared our pnr status has been changed from 2ac to 3ac (This thing happens only with us) & we forced to travel in 3ac while we paid amount for 2ac and deducted the same from our account.
For this incident (Degradation of 2ac to 3ac) we dont have prior information & suddenly we have to travel in 3ac.
My complain is that we spend our money for 2ac not for 3ac (In 3ac very bad washrooms with bad smelling and no water) why this thing is happens?
Will be get our refund for 2ac?