If you want to try to get rebooked to the next Hainan flight, only Hainan can do it. PG can't/will refuse and Exp is not going to take any responsibility here.
It seems that it was PG at fault because refused to tag bags to final destination on a through ticket. There was only 1 ticket and it was on Hainan ticket stock /the ticket No. starts with 880?
But I doubt you will get very far with this. Only option seems to rebook the Hainan flight - or buy a new ticket to China if cheaper.