It is a scam. Most likely, the vendor is also the scammer and the payment will eventually be reversed. Never accept money that you have not earned and is not yours to keep to do with as you like.
Now that you know this company is trying to scam you, I strongly urge you to cut off all contact.
NEFT transactions can't be reversed by the by the individual. Transfer into Escrow account depends upon the conditions attached, your bank should be able to confirm. Escrow accounts are expensive and done for large transactions, in which case please also take the advice of a lawyer