Hero Motocorp - Horn not covered in warranty gaurantee

Sir,
I purchased a new hero duet in Oct ****. The two wheeler is within warranty period. However, horn become unserviceable after * months of purchase. When i approached the dealer M/S Baba Hero, Near HP Petrol Pump. Raikot to Mullanpur Road, Sudhar-****** (Ldh) Punjab he informed me that horn is not covered in warranty clause(Although, horn is not included in the list of parts which are not covered in warranty as mentioned in the service book of two wheeler). The cause of concern is if horn, brake, clutch are integral part of any vehicle and are essential for road safety. Then why it is not covered in warranty clause (as per dealer). I therefore request the forum to quantify the matter under road safety as if an integral part like horn is not included in warranty, manufacturers are free to sell vehicles with substandard part compromising road safety.