After persistent inquiry, ChatGPT says that a combination of a dopamine antagonist (Meto, Domperidone) AND Ondansetron (single dose, it seems) is now recommended in the PPH. But don't ask me how to get Ondansetron.
So I'd use Meto (regimen) and a single dose of Ondansetron if I'm able to get it... I hope it makes it more likely to succeed with only one chance.