Update :
Cyrus Poonawally known as "Cyrus the Virus" (he owns a company manufacturing vaccines) paid the USD 5000 or so expenses for the five weeks in India.
However the fees are still unpaid.
Personally I prefer a verbal agreement or a handshake for any work I do, and up until now that has been more or less ok.
Here in india, corruption is so endemic and normal that even if everything is in writing, it makes no difference. You may as well count on a handshake because there is no way of taking the matter to the courts.
India ratified the UN Convention against Corruption in 2011. Only since then has "trading in influence" been illegal i.e. to influence the Police or a Judge concerning an investigation or court case. Same applies for instance to;
bribery in private sector
bribing a foreign public official
embezzlement of property in private sector
obstruction of justice
liability of legal person - companies are not liable for corrupt acts of employees
In essence, no way to recover the money that is owed. Cash in advance is required here unless the Principal has a good reputation.