Maruti Suzuki — Defect in Ignition Keys

I purchase Maruti Stingre No. GJ 4 BE 9340 from Eternal Motors Gujarat in September, 2013. Surprisingly, one day car did not start with the key which I was usually using, then after going through manual I used my other key and car started. When I contacted service Centre it was told that there is defect in key's programming and keys require to be replaced for which there is an expenditure of Rs.3500/-. My car is under extended warranty. Defect in the programming of the keys not a manufacturing defect and as such the replacement/repair of keys to be done within the warranty. Please advise me urgently as I am using my car with one keys and in case of any emergency I may be in trouble. Thanks & regards O P Yadav