well most us who use credit for atleast a couple of year, know all these tricks.. i wont blame ur friend totally, but yes, this happened to her bcoz of her carelessness.
these are the basics of credit cards. and some one who is regularly using card to spend like 30k per month, infact should be more educated abt these devil plastic stuff. Your unawareness can really take u for a ride.. Enjoi..
