Regarding battery life of Honda Activa i?

I'm really shocked about my Activa i's battery life. I've been through just around 3.5k Kms and I've bought this just before 4 months only. But my bike's horn is not working, self is not working and sometimes it gets suddenly off while riding that too in the middle of the road. Can anyone please do help me regarding this for whom do I need to complain or how to check whether the battery has been replaced when its been serviced. This is happening since after just 4 days after getting it serviced(2nd service).

This may not necessarily be the bikes battery. Remember that the battery charges when the engine is on, it's not like you drain it and replace it. It could be another electrical fault somewhere else, such as the battery not charging quickly enough to keep the electrics alive.