Bajaj Auto — issue in my bike chain

Address:

Laldarwaja, Ahmedabad, Ahmedabad, Gujarat, 380008

Dear sir,
I bought bajaj platina on 26/10/2018 from amin bajaj automobiles laldarwaja branch. I started having problem in chain after 2nd service. Chain was getting loose and the noice of clashing of chain and chain cover was coming. For that same problem i went there for seven times in just two months. To be very honest i don't have any knowledge about bikes so i gave my friend to drive so he said that the bike is pulling back while changing gear so i tell my friend to give my bike in service station for resolving those problem on 10/06/2019 and they called me on 11/06/2019 and they said that there is a problem in clutch plate and said the cost would be 1800rs. They said that clutch plate would not cover under warranty and said they already written in owner manual book. But the issue is that we get the owner manual book after buying that bike and they didn't give that information to us as well. And every week they give advertisement of bujaj bike of 5 year free service and warranty which doesn't make sense. They need to inform everything to the buyer before buying but they didn't give any information to us. After that i went to service station on the same day and talk with the branch manager for the problem in bike. So i ask the branch manager to give me in written that i had also attached under.
Sir i request you to please help me with this problem and try to cover that in warranty.