Maruti Suzuki India — Servicing and repair

Hello i have given my car for servicing and a repair that the new battery getting discharge while parking overnight.A month ago i have given the car for same repair they said to replace the body unit(BSU am not sure) and i change it for 14300rs but no use.Again i have given the car for same problem they kept my car for one week without resolving and they are saying to pay the bill and take your car and show to an authorized mechanic.I have trusted the maruthi suziki for 20years and will continues but this type o[censored]nreponsible service centers must not accepted.please send someone experienced to repair my car.