2 months new car already has problems

Hi I’m not happy at all they did nothing to my car except take the diamanté deco on the starter. Now I have more problem it stops randomly and when I took it in I told them my brother said they must take the petrol pump, change the battery and the starter because he listened to it. I heard them when they spoke to you and you say hyndai would pay for them. Upon checking their system they also realize it was only serviced once and they asked how does hyndai sell a car that is not serviced. Plus they use some of my petrol I know that might sound petty but I’m adjusting to paying an installment which I have never payed I’m adjusting to paying insurance. And now I two months I must park the car and make up money for starter, petrol pump and batter.