I need to find an agent in Bangkok to receive a passport, make a small cash payment to a bank, deliver the passport to the Embassy with other documents, pick up the passport, and mail it back.

Does anyone know agents that do this type of thing?

That's not exactly how it's usually being done, but I'd guess if you contact a few, you will find one who is willing to help you. The embassy is fine with applications by third parties, no interview etc. ?

You may have seen my earlier post about having the passport delivered by DHL or FedEx to the Embassy, having a prepaid envelope with it to send back.

Unfortunately this Embassy says they don't receive deliveries, you have to find some kind of agent to hand deliver it for you. And also their only payment method is to pay a small amount to their bank account. Kind of fussy and inconvenient.

We have all the paperwork completed and approved via email, it just needs to be delivered and the payment made.