Aggressive renegotiation between exporters and importers in Colombo

In Colombo port in Sri Lanka, a negative trend has come up.
Many importers are unloading the consignments from the ship to the port and then not paying up the exporters.
The importers are aggressively re-negotiating to reduce the price with the exporter before taking the final clearance from the port, for taking possession of the goods.
Most of these cases are related to grains, Indian chili pepper and red chili and other Indian spices.
Exporters have notified the DGFT about this trend and requested for help.