State Bank Of India [SBI] — false billing by sbi card

Address:

Mumbai City, Maharashtra

I have purchased something online costing 9449/- on EMI using SBI CARD, the same was cancelled by me on the same day, the online agency refunded the amount and credited to my card. BUT some highly intelligent persons hired by sbi card failed to cancel the EMI and made me pay those EMI, as i had my trust on SBI Brand, i used to pay the outstanding amount on due date, when i checked i was shocked to know that i had paid 9449/- (the cost of the product)
for something which i had not bought. After writing to the nodal officer they had refunded me RS 223/- and they have no idea about the rest of the 9226/-.
Kindly help me out of this misery which had already harassed me mentally and economically.