What if Seller-on-line Shopper Cheats the on-line Purchaser?

I R Srimathi, ordered a new mobile phone from "Rediff.com" (a on-line products seller) by Cash on Delivery. I booked it on 15/04/2015 and rediff.com (on-line vendor) confirmed it on 16/04/2015 and despatched it on 17/04/2015, and on 19/04/2015 it was delivered to me in the Evening (16-30 Hrs) after receiving the Money (i.e Rs 5087 inclusive of delivery and handling charges) I opened the parcel immediately and to my rude shock it was a FAKE (repaired old mobile with new covering body). It was really a rude shock for me. Same day night I mailed a letter informing the on-line Seller about the FAKE product I received from them. From 20/04/2015 till today i.e. 05/05/2015, I am in touch with them through on-line mails and through mobile (almost everyday I spoke to different person and I noted there NAMES ). They went on promising me that they will arrange for a pick-up within 2- 3 working days , but till date NEITHER they ARRANGED for a PICK-UP from there end NOR they allowing ME to despatch through a BEST Courier service provider. Today I spoke to Customer Care Service rediff.com and requested them stop this DAILY ( it is really harassment to me ) mail to mail and arrange for early pick-up of the FAKE product. The customer care service as usual asked me for 2-3 wait for the PICK-UP Service. I am really fed-up with this, Kindly advice me WHAT I should now? CAN I FILE A CASE? IN CONSUMER DISPUTES REDRESSAL FORUM? waiting for for your early REPLY. R SRIMATHI ( srimathinavale@gmail.com ) BENGALURU 9342703910/8792821492