Tata Motors — Nexon Diesel pick up issues

Hi team,
My Nexon Diesel is having pick up issues when we are driving with 4-5 occupants. Also have issues in hill climbing. It is not smooth on 2, 3 gear and everytime I take to servicing they say there is no issue. For even small slope I have to put it in first gear. While increasing speed it pauses for few seconds and then picks up.