Hero Electric — Regarding cheating of the dealer

Respected sir, in june 2016, i reserviced the hero electric bike optima plus with new battery and new horn, in the battery it is given 12 months warrenty and even the dealer told the same. But this month of may they are not willing to change it. If the dealers cheats, how can i recommended this product to others. I would only give bad reviews on our product.
Date of purchase of bike :24.10.2009
Date of service: 13.08.2012
Date of reservice: 16.6.2016.
The battery replaced on 16 june 2016 had a problem in the month of may requested the dealer to check, he checked in the month of june and says only 6 month warranty for the old bike. As years pass the bike will not work properly. If it so then the electric bike is a worst.
Dealer: sri sai automobiles, thilla nagar trichy.