Cheap vendor warranty and poor grievance redressal

I love Tiago always, but when come to maintenance company is cheating customers by providing cheap vendor warranty for parts like Battery. They give standard warranty of 2 years. But battery warranty is 18 months. My car is now 22 months old, but have standard warranty . In the last service TMSC advisor give an insight that my battery condition is poor and describes me this warranty terms while asking for replacement.. They are cheating by providing low warranty and compromising the quality from vendor. Because same battery can be purchased outside in 5000INR range amount with 3yr warranty. But OEM battery only got 1.5 years only. I also send mail regarding it, reply is an auto generated message with contact no., I called state level service manager of tata over phone call, he doesn't even know to address the issue empathetically.