When can an ATM detain your card? If:
you enter the wrong PIN several times;
the card is restricted;
the card has been expired;
the card is physically damaged;
the card was not taken back from the reader for too long;
There was either a reader or machine failure.
If the ATM machine froze, turned off during a transaction, or the reader stopped working, please wait for a while (about 5 minutes) because the machine may restart. If that happens, ATM will eject your card, and if you leave the ATM too early, the card may be taken over by a third party.
In case the card is stuck inside and there's nothing else to be done, notify the ATM operator about the card retention/machine failure. Each ATM has a sticker on which an emergency number to call.
Then let us know immediately. For the security of your funds, the card should be blocked.