I'm a bit stuck!

I've been working on a Parish Plan Questionnaire which is now finally finished (after umpteen drafts, changes, more changes, and committee decisions) **Much eyeball rolling needed here!!**

It needs to be printed as a stapled A4 booklet - ie duplex printed onto A3 paper.  I've created it as an A4 document and I rather assumed that, as A3 is just twice as large as A4, that they'd select to print multiple pages per sheet and hey ho print it, staple it and fold it.  Mmm not that simple said the girl at the printers

It's due back at the printers on Monday morning and apparently I have to re paginate.  It seems that the printers just produce it and couldn't give me much help on the design side.  Help?  Do any of you know what I need to do?  Normally I'd make these choices using my printers software but as it doesn't take A3 the option isn't available so I need to put the solution into the source doc.  Please can someone rescue me :)

By the way - I've created it as an MS Word document.

could you go to your local library and photocopy it on the enlarge setting A4 to A3?  Not all libraries have colour printers but it might work.  The other option is to find another printer and take your memory stick to them and ask them to do it for you.  Not much help but worth a try.