SBI Credit Card / excess payment issues

hi
I had made a purchase on my SBI credit card for which i had credited an excess of 200 to my credit accout. Since I cannot with draw the amount I decided to use the card in another merchant location and purchased mechandise for about Rs. 293. I then remitted a amount of Rs 200 to my crdit account and hence I had again made excess payment. I havent been getting the credit card statements (about which I ad already raised a complaint) for some time and thats why i have been making the excess payments.
Before my last payment(in July) I called up SBI credit card (sometime around 4- July-07) and asked them about my outstanding payment. They said that my payment date was 30 June 07. ButsinceI didnt get my statement they would consider this and wont charge me any late payment. and hence I paid Rs 00 to my bank account.
After making the payment I made a call to the guys and they asked me to call after some time since their server was down and so I called up after 1 week. This time I waited a long time on the call for them to get to my credit details, since I had already made a payment to them in excess I felt I need not ask them if there were any outstanding on my account.
The trouble started when I called up the credit card number day before yesterday (27 Oct -07) , they said I am required to make a late payment of 900 Rs because I had failed to pay on time in the month of June. Actually I had paid an excess of Rs 100 /- at that time but still they ask me to make the payment.
They dont even show the courtesy of sending the statements and now they expect me to know about my transaction details.