E.c.g.c. Claim Settlement

Dear sir we are merchandise exporters importers having valid license from different departments of government of India and have exported rice to Dubai after getting policy cover from ECGC. The term of payment was 50% against documents and balance after 30 days. However the bank of the buyer refused to handle documents of the buyer. So we were left with no alternative than to deliver documents personally to the buyer as the shipment had already left for Dubai. ECGC refused to settle the claim on the ground that terms were different. You are requested to kindly write us how we should proceed to get our claim.