Useless method. Till Payment Done u won’t get “Confirmed” and “Payment Done” statement on the itinerary . Just use photoshop to do it urself. With “Confirmed”, “Payment Done” statements on itinerary paper.

No need any agency. Just go to ekkamai bus station take a minivan before 8 am, a minivan(200baht) Arrive there around 12pm. Just walk 200 meters to border, departure Thailand. Walk right side get Cambodia visa( if need) 1200 baht. Then walk in Cambodia. Then walk out. Pass the Thailand border. Go straight the same bus station. Take a minivan to bkk 230 baht. Arrive here around 6 pm. What I did 1 week ago.

I done twice. My return flights ware at 5:10 pm. Reached airport like 4-4:30 pm.

Samut prakarn will charge u for it 1000 baht as I paid twice and won't extent until forms filled by landlord . Cheang watthana is fine. Just do it at cheang watthana.