Convert an existing 8.5\"x11\" sheet to A4

We presently have marketing material designed for North America formatted for printing on Letter Sized sheets. We need to reformat the sheet for Europe to be printed on A4 formatted paper. This project may sound simple, but the original sheet was prepared in word, and the way the graphics and text exist on the sheet causes everything to go awry when you try to manipulate it. I need someone with superior skills in word, or other platform to take the existing work, and adjust it to A4 format for us, and deliver the work as an editable word document in A4 format. We need to use word, as we frequently customize these sheets to include the address and contact information for our reseller partners.