then from day to day, he said his supplier also can't make sure can get the stock.

This is the main problem.. If the seller knows the supplier cant get the stock or no immediate stock. Dont ask buyer to bank in the money, now see many problems occured.

Supplier no stock also wait supplier restock then ask buyer to bank in. Not say directly bank in to him then ask supplier order the stock, the stock when reach also dont know. Later supplier con the seller more worse..