Rust on door sliding door by handle

[Tridini]

I have an 08 plate California and have rust around the sliding door handle. VW will not honour the corrosion warranty which is 12 years as they say it is a paint warranty claim that is only valid for 3 years. Has anyone had this problem? VW have also changed the handle design to stop this issue according to forums but VW won't admit that this caused the problem.