Finally, I just paid again and sent them the receipt for my second payment. And submit a request through web form for retrieving the receipt for the first payment and refund. Worst case, just lost that $2080 if I cannot get the refund back. I have been waiting for 8 years to be selected for the PGP application. Thanks everyone in this forum!Pay again and send the application and deal with the refund later. I wouldn't not delay sending it over the payment. Bad, bad, bad idea.