UpdateBounds with Paper Size

I am trying to do the following:
1) The printer page is A4
2) The User Set a Custom page to A3.
Tha problem start as soon as i open the saved file my margins is messed up.
After Loading:
After Update Bounds:
In the past I called UpdateBounds and the sheet is nice in place but with the cutom papersize I can't call Updatebounds any more.
please advice me on how can I override Updatebounds or what is the properties to set after loading a file to realign the custom papersize with the current printer margins.

Check the other parameters in the PageSettings object… perhaps changing to custom changes something besides the size?