Rights Of Return What Rights Do I Have To Return Without Penalty A 4 Day Old Car That Will Not Start?

What rights do I have to return without penalty a 4 day old car that will not start? - rights of return

I have just bought a new Mercedes E-Class diesel was broken and refused to start after it was 4 days - the first distributor of more than a week and are incapable of looking after the failure so far.