^^ CC number and expiry date can be abused. Without CVV, you will not be able to make a transaction, but with last 4 digits of CC number, expiry date in conjunction with date of birth and name can be used used to authenticate yourself as a genuine customer to customer care of the bank and use it for mischief.. You can request for the card to be blocked, register for unnecessary paid services etc. Even more severe forms of abuse has been done in the past.
Also CVV2 is usually a 3 digit number, it takes under 1000 tries to crack it if you already know the full credit card number. You can use credit card number, expiry date and CVV2 to make transaction on many foreign websites.
Do not give full credit card number to anybody, genuine bank reps will only ask for last 4 digits of the CC number and date of birth for verification. Some might ask for registered address.