Royal Enfield — Complaining about the issue of engine leakage

I have purchased BULLET 350 ES before 4months and the bike engine has been leaking from 1st month of it
Service centre says that is normal this issue is in all bikes and when we go for a free service they gave us unusually expenses that the bike should not need
They don't do work perfectly and told us many expenses to this regarding about the issue please give me the solution about this urgently