Honda siel cars india-honda city
Leakage in the boot space

I had purchased honda city 1.5 s variant on 10th of may itz hardly done 20 k kilometers, when i got it serviced last month it came to my notice the rear boot space had a leakage problem and i was told by the dealer that the holder of the spare wheel had been broken cause being it was rusted.now i want to know who's responsible for that? when i have a warranty for 4 years.