Mispresentation of vehicle by dealer

My sister just bought the car at Auto Pedigree Brits branch on the 15th August 2022. On the day of collection my nephew noticed that the tires were worn out and there were scratches on the car. They were then told to take the car and bring it back on 29 August, as they will book for it. The scratches were fixed and tyres replaced, but unfortunately since the car has been dropped to them, the dealer is now playing hide and seek, he keeps on saying the manager will phone my sister to explain. Today they told my nephew that the person whom they car to said he hasn't done it. How can my sister cancel or get help in this case since she has not even paid first instalment but one can tell that there is something ***** with the car.