Replaced sliding door, slightly misaligned and possibly causing a leak?

[pocketcup]

I've had my Ex BG Caddy for a month or so. I noticed some rust on the floor between the passenger side wheel arch and the sliding door step. After a bit of rain the other night there was a bit of water where the rust was. So obviously this has been going on a little while at least.

I've now noticed the sliding door on this side is slightly forward towards the B pillar a few mm. Looking at the service printouts I can the see the same door has been replaced.

Has anyone had a leak from a similar issue? Also how do I go about adjusting the door position?

Thanks for any help!