Yesterday I was going to buy fairly expensive item on the internet,
When I entered credit card number, next screen was error page which display “you can’t use this card!”.

I checked limit amount, But It was enough to buy it.
I tried to buy it by another credit card, but it also failed.

Today , I got a phone call from the credit card company,
The operator told me that yesterday’s purchase was not considered to be normal. so their system locked my credit card.
The company called me to confirm that this purchase was done by me.
also they unlocked my credit card status.