BF water leaking

Water is leaking into the boot of my BF MK2 XR6 where side panels bond together underneath rear widow. There is little bit rust on top, but there is more inside. I went to few secondhand dealers and find out that there are lots of cars with the same problem, and it looks like it is common with this model. Do you think can I ask Ford to help me to fix this problem, because car is just over four years old?

We had quite a number of reports of water leaks into the cabin and the boot with the BA, which had real build quality issues, but we haven't had reports of later models suffering in the same way. I would have a panel beater look at the car to assess where the leakage might be occurring and if that suggests it is a build problem then you could approach Ford for help. But I wouldn't hold out much hope of you getting help with the car being four years old and out of warranty.