These currencies are normally used by criminals operating on the dark web or the hidden web. Legal, bonafide businesses do not normally use Bitcoins. Therefore any request for business transaction in Bitcoins should raise suspicious and should be avoided.
The legal framework regarding crypto-currencies is yet to be laid down. RBI has not given any licence/authorization to any entity/company to deal with any virtual currency.
In the absence of a legal framework, it is not advisable for citizens to deal with virtual currencies such as Bitcoins
How to make a complaint:
In case you are a victim immediately report to the police along with following documents:
1. Complete facts in brief about the incident.
2. Address of Bitcoin.
3. Amount of Bitcoin involved.
4. Address from/to whom purchase/sale of Bitcoins is done.