Refund of amount paid against Demand

I had a demand raised by CPC, so i had filed a rectification return, but as it was taking time to process, i had paid the demand due. Now the rectification order has come and it is showing what I filed in orginal return is correct (all the particulars matching to orginal return), and there is no payment due (they have not considered what i have paid against demand). So how can i get back the amount paid against the said Demand?