Seem to get stuck with things that require a fight, but I am more than up for it...
Best one was 4 years ago I had waited I think 3 months to take delivery of a brand new Chrysler 300C Touring. Car was on lease through Mercedes-Benz Finance, sourced through a UK main dealer. Woke up early for it arriving and looked out my window to see it on the flatbed being delivered, only to notice that the passenger door was pulled back at the top!!!
Closer inspection revealed the car had suffered an attempted break in whilst at a dealer compound, but when it was checked before delivery to me (it never was but they stated it had been) this was missed. Amongst other issues were badly damaged paint due to bird poo that had been allowed to sit on it for months and scuffs and stains inside the car on the light grey leather.
I rejected the car that morning and sent it away...the dealer initially accepted responsibility verbally but what followed was 8 months nearly of trying to either get a replacement car or the finance deal quashed - all the while M-B finance were charging me my monthly payment (which I refused to pay, but they had my deposit) and my credit history was going down the crapper.
Chrysler Germany were involved, specialist engineers, it was a joke. In the end I threatened to take it to the papers and issued formal letters and the finance company acted quickly - but then at around 3 months and after signing novation papers to transfer the deal to another buyer, it all went quiet and I heard nothing more until the following year.
Nightmare situation on what was the best I car I never owned lol...