my bank in india has submitted docs to construction bank of china on 12 aug (delivered by dHL).

Their bank sent a message on 21st Aug stating that even though date of BL as per docs is correct as per LC, our client has "investigated" and found  that ship has sailed late.

 Further the message states that we "tried" to relay this message on 19th but could not.

As per UCP 600:

1)Their bank responded after 5 days

2) The BL date is correct as per LC however bank is acting as advised by Chinese customer. 

The reason for refusal is the price of commodity fell sharply furing voyage period of 15 days.

What should we do ? where can we complaint against china construction bank and get our money?

My bank is state bank of india