The Opposition has severely criticised the Centre for the move. However, Jaitley justified the decision saying the government couldn’t have calibrated ATMs for the new Rs 2,000 and Rs 500 notes and still maintain secrecy. “Any such move to recalibrate would need thousands of people and the secrecy would be compromised.” “It would have given the whole game away,” he added, admitting that any change in ATM-related technology would need time. He advised people to not go for exchanging currency in the first three to four days, saying the window for any such transaction was open till December 30.