Could it be that your submissions are not correct. The system does work I got mine within 4hrs of submission. Make sure your uploads of vaccination cert are clear good jpegs also crop the QR codes from your vaccines with very little border. Upload for each vaccine where it asks for QR Codes Be sure that your accommodation clearly states pick up at airport covid test on arrival and lateral flow test for day
yes screenshot the NHS certificate of vaccination, then crop each QR code as a separate jpeg. You then upload the full certificate for vax 1 and the QR code for vax 1, same process for vax2 on the Thailand pass app. It all works best if you use Google chrome and a Gmail address.