Kept in dark by the seller

Dear Sir, I purchased an AC of LG on 15 August from an electronics dealer who deals in several brands. The purchase was made through Bajaj Financials services under loan scheme. The total amount was of Rs 49,000. The down payment amount was Rs 17,275 of which I paid Rs 5000 and gave a post dated cheque of Rs12,275. The dealer sent his technician for installation of the machine on 21 August 2015, the same day which was given on the post dated cheque. Just after installation I found that the AC had not the feature of 4 way swinging, instead it has only 2 way swinging. I immediately call back the dealer and told him that he had not told me this face of 2 way / 4 way-swinging feature. Instead, he had told me that there was only one model in Inverter AC range and therefore, I had no option than to buy that particular AC, if I had to buy an Inverter AC. (This, he has accepted in telephonic conversation as well in person conversation and I have the recording of both i.e. telephonic and in person conversation). Later, I found that there is in fact, two models in Inverter AC category and the second model has the 4 way swinging facility. Thus, the dealer kept me in dark and cheated me. As a matter of fact, I send an application to the Bank Manager to stop the cheque. Now, the dealer has sent me a legal notice U/S 138 of the N.I. as well under U/S 403 and 406 of the I.P.C. stating at my cost. The dealer has done this in spite of saying me several times on the phone for one month that he will replace the machine. However, earlier he had said that he will not replace it. I have the audio recording of this telephonic conversation. Please advise me, what should I do now? Please give your valuable advice. Now, I have made up my mind to pay the amount. Should I still need to reply the legal notice served by the seller? Can I file the case in consumer forum now? Please give me the advice. Regards Shashank Shekhar