Exporter: refund of service tax

Hello,

A Pvt Ltd Company is a 100% Exporter of Tyres. Now, it has paid Service Tax on CHA, Clearing and Forwarding Expenses, Banking Services(Bill Discounting) etc.

Now I've applied for Refund for FY 12-13. There were 184 invoices but payment of 31 invoices has not been received and will never be received. Will and Service Tax paid for these 31 sales not be refunded? What if the payment is received after say 2 years?