What is really needed is for our Federal Gov't to do its job and protect the US Citizenry from what amounts to the actions of a foreign enemy.
If it can't be accomplished via diplomatic channels then perhaps a few drones striking the buildings that house the scammers would "discourage" them preying upon American citizens.
Wouldn't even have to arm the drones with explosives. Design a way to release roaches, rats, stink gases and any other noxious but inert gases ...I mean a few - relatively very few - people would get injured but hey...they should learn that fucking with American citizens (especially our vulnerable older people) will bring serious consequences.
Also it might be effective if the US State Dept. cancelled or voided all work visas of India natives who are either already working in USA or going through the process to attain a work visa for USA employment.
Tell the India gov't - stop the scammers and we will re-activate the work visas.
IMHO US Federal Gov't is failing to do its duty to protect the victims of the scammers.