Same here, my hotel pointed me to psas web site although I told them it is broken and asked hotel to process my payment for tests or advise of any agent but they replied to me that I should try psas web again as they 'fixed' it (not true).
Then I decided to register for PASS. I filled all the fields and attached all documents, funny they accept some docs in pdf but others as png or jpeg extensions, so more trouble for me to convert files to accepted format.
The last page was to report PCR tests and submit receipt which I don't have. I made screenshots of scheduled appointments and failed payment processing, and finally wrote a letter to embassy explaining all the problems with psas and asking for cash payment option on arrival, then submitted all 3 files.
I got successful registration and received email with control code.
The PASS system may reject my request for sure but at list I reported a problem and I will use AQ.IN.TH as the last resort.