Delay in Service Tax Payment

Due Date of paying service tax is 5th of every month Actually service tax was pd on 5/2/08 , but in stax form some challan number was not mentioned due to which bank did not processed the payment of service tax on 5th & actually got debited on 7th. of this month. Bank has acknowledged dated 7/2/08 in the challan.Ofcourse i know there is default in payment. Will there be any interest amt payable?? If No what should be the next procedure Kindly revert at the earliest.Rgds Ramesh iyer