Logically, Once the status is allocated to any class ticket (3 Ac, 2 Ac, etc) then it shall not be downgraded..... It will upgraded as per the system. e.g if you are having 5 TKWL then you can have either cnf ticket or might have wl between 1 to 5. But it cant be TKWL 6.... Same as the the passenger of sleeper class may be upgraded to 3 Ac, so as 3 ac to 2 ac... Here in your case also, once your ticket gets cnf, the IR cant stamp it as wl... If you have neccessary proofs, you can talk with the respective Station Master of the ticket booked by you and can ask for the demage that has caused to you if any...