SBI Credit Card — fraudulent call

on 3rd march a fellow named Rahul chauhan phoned up and read my credit card no .said he is converting my reward poits in to cash and asked for OTP. i asked him how to beleive ? he said he is senior manager from sbi main branch in mumbai and he said his mobile no is (from which he rang) [protected].the next day one lady calling herself riya sharma (mob no is [protected])called and said that a letter to this effect ie the reward poits converting in to cash will be despatched to my address and got it noted down from me. same day i saw the sbicard and it was showing debit of 8888.00 and the same day i emailed to feedback @sbi, sms ed them but to no avail.so far no one even responded till now.just now saw the same no quoted here in this website. this means that fellow is a fraud ?? then knowing fully his mobile no why cannot he be caught by the police? anyway i am determined not to pay for this. pl help . s seshan