Repeating report headers on every page (SSRS 2012)

I have a report with 2 subreports. The 1 subreport consists of a matrix which has columns increasing and decreasing depending on the parameters chosen. In some instances the subreport grows and spans over more than one page. This is fine, but I have a "page header" which has to repeat on every page and change with the grouping created on the report.

 Attempts:

1. I have tried putting the data in the page header of the Main report. I then put hidden text boxes in the table, referencing them in the page header. This worked perfectly until the subreport grew so much that the hidden text boxes weren't on the page. I added more hidden text boxes in other positions to try and reference them when they are on that specific page. Error because we can't reference more than one report component in the page header.
2. I tried putting the header into a the main report's table header, it would not repeat when the report expanded over the page horizontally because the cell is now being spanned over the 2 pages.
3. I tried to put the heading in the subreport's "page header". The page header does not pull through to the main report.
4. I can't put the header in the subreport as a table header, since the heading has to be centred on the page and I can't merge fields horizontally across the matrix.
5. I put the header in text boxes just above the main report's table, repeating with the table, the text box only displays where the first subreport starts.
6. I put the header in text boxes just above the subreport's table, repeating with the table, the text box only repeats with that subreport (obviously).

Any other suggestions out there?

Thanks