How did they debit your credit card as you have done no transaction with them?

Fraudulent Transactions

Fraudulent transaction is any transaction that takes place in your account that you did not authorize. This includes someone physically stealing your card and use, and where the number has been compromised, while the physical card is still in its possession.

When the card is stolen, the most common fraudulent transactions will be gas stations and fast food restaurants. Most thieves are going to fill them and the vehicles of his friends "with the gas you - at least, that's their thought process. They will also go to eat, somewhere easy and quick to escape in case there is a problem.

When your card has been compromised, the most common operations are transactions online. Your card may be compromised in a number of ways. There have been cases where waiters in restaurants have been writing the numbers when customers have used them to pay. There are also small scanner attached to ATMs and gas pumps that collect data and the thief can pick up at a later time. It is very important that you be alert and carefully you hand your card to.

Source:
http://www.moneymanagersllc.com/