Maybe try to contact them on Twitter. It is common to see companies being much more reactive there. Agoda often has the best deals in Asia ; it would be costly to avoid them.
I think I totally screwed up with the new process. The days where you could show up in person and take your passport with the single visa the new day at the Consulate are over it seems. You need to book 2 weeks in advance in Ho Chi Minh. I did the e-visa process but again it seems you need to wait quite a long time. I did it 5 days before my flight. But I probably will go to Thailand on a visa exemption and extend there as I might not get that bloody e-visa in time.
We can't really say it is really a scam as we take the reponsibility to risk it while knowing exactly the risks. The second test on day 5 is still a ridiculous policy because as you said, it means you can get the covid in Thailand and pay a huge price for that. It is advisable to postpone any 2 weeks vacations in Thailand and choose another country at the moment. Philippines are opening on the 10th of February and they don't have those absurd policies.
Pretty sure you need a PCR test if you are not vaccinated 48 ou 72 hours before. It has been the common rule since the beginning of COVID for travelers who fly.
I had those 20k last time at the airport but damn this is so inconvenient to carry so much cash when travelling. Any report about travel cheques? I heard they should work as proof. At least if you lose it or get stolen you don't lose the 20k.