Rediff Shopping / Multi SIM Mobile Phone — Failed to deliver Genuine goods

hello.
I am Dr. chaitanya, from hyderabd, purchased a multi sim mobile phone from Rediff shopping order N0 4675902. in the month of june, but rediff sent me a different model, which was not working, On my compliant the phone was picked up from my home for an exchange but did delived me the same phone after 15 days, on my second complaint No action has been taken tilll now, Rediff site is deducting EMI from my card but is not delivering the phone.
Please tell me what action can be taken on it.
advise
regards
chaitanya