Honda 2 Wheelers India — honda activa 125

Since the last few days, my honda activa 125 stops on it's own while engine is running & then fails to start. I have bought the vehicle only 4 months ago. I have visited the service centre at-least 4 times on consecutive days but the problem is not rectified. Each time i am told that it's an issue with the fuel. I have tried getting the fuel refilled from all the possible gas stations but the problem is still there. The service technician is refusing to acknowledge the fact that there can be a technical fault with the vehicle. I told him that i have started facing this problem only recently & that if it was actually a fuel issue then i should have faced this from the beginning. I have tried re-fuelling the vehicle from the gas station they suggested but the issue is still present. My vehicle is still under warranty. I want my vehicle to be replaced with a new one since the fault is not getting rectified. Please assist.