ICICIcredit Card — Settlement-Voided-repayment-hurrashment

Dear Sir/Madam,
I am kasi and holding ICICI Credit card.
I have used the Credit card services of ICICI Bank and thanks full to them first of all.
I have done settlement on july of 2008 and everything was fine.I have made an settlement as per the ICICI executive for Rs 18, 000.
But after 3 months, i have got a cal from ICICI bank regarding the credit card balance.
I have got shocked and i complined to bank but they are telling as...your letter got voided and you need to pay the whole amount.
I am in a depress mode with their call and i lost my confident.
I have a letter with me.
Can any one plese responde like to whom can i contact and complain?.

Please revert me.
Thanks,
Kasi.