(!) Now-a-days many buyers placeing orders with some advacne: but the supplies with good faith enter into production and ship on ** basis.Sometimes the buyers are not interested and abandon the shipment:

(2) Getting the advance,some suppliers are not maintaining the agreements: a) makeing inferior quality than agreed b) delaying the shipment:

In the aboev cases how the buyers and sellers solve the problem through whom?

Replying to [curdrice]:
Not through anybody but Seller and Buyer themselves.
How to overcome cases like that from happening? well, Buyer has to pay the goods cash upon loading or via L/C but use SGS for inspection upon loading