Citibank Credit Card — FRAUD TRANSACTIONS OF RS. 50000 ON CITIBANK CREDIT CARD

DEAR ALL,
i am using citibank shoppers stop credit card for last 8 months. which i rarely use for purchase or other transactions. recently i found that my bill is Rs. 50000 in may 2008. i hvn't used my card anywhere & all transactions made to BHARATI AIRTEL, RELIANCE INFOCOM. i dont hv any post paid connection of mobile, landline phone. i hv registered complaint to POLICE STATION. copy of FIR sent to citibank chennai ofice. the card is still in my possession. i have also called up AIRTEL CALL CENTRE but no use. they can't trace these transactions. CITIBANK officers say these are the secured transaction made on internet. but i dont share my card info wiht any1.

if anybody here is facing same problem then plz suggest me solution. i am worried abt this.
TANISHA- MUMBAI