Blunder to buy Tata Nexon

Hi, I hv purchased tata nexon xz+ diesel car, since jst within 28 days after d first service, I'v experience d constant irretating soung from d engine n my car drop its power n pickup. Service provider does not exactly explain me d problem, n yet I can't get my car back. It's a blunder to trust on Tata cars, its a huge mistake.