Make manually changed pivot table column headings work for other u
 

I have a pivot table in which I use a date field as my columns. I have used
the Group function to group the dates by financial year: our financial year
runs from 1 June and I have a few years' data, so I have grouped from
01/06/2005 (English date format!) to 31/05/2008, with grouping by 365 days (I
know that will cause problems on leap years, but that is a separate question!)

My column headings therefore show as "01/06/2005-31/05/2006" and
"01/06/2006-31/05/2007", etc. For neatness, I have manually overwritten
these column headings, so they are "2005-06", "2006-07" and "2007-08". I use
these headings in a GETPIVOTDATA formula elsewhere in my worksheet too.

This is all fine, and works as expected. My manually changed column titles
stick when I refresh the Pivots, and when I close and open the spreadsheet,
etc, and my GETPIVOTDATA formulae continue to work.

However, when I send the file to another user and she refreshes the pivot
data, the pivot table column headings reset to how they were before I
manually changed them (back to "01/06/2005-31/05/2006" instead of "2005-06").
The GETPIVOTDATA formulae then don't work for her.

Is there a way to make the manually changed titles of the grouped pivot
table columns stick for other users? Is it something really obvious I am
overlooking?

Thanks in advance
Katy