PDF edits and fraud

I was given a print out of a financial report that was printed from a PDF file.  When I started looking at the numbers on the report, they did not add up correctly.   The line items appeared correct., but when I manually totaled them, the totals were all wrong.  When I questioned the numbers and ask how the report was prepared. I was told that a PDF file was downloaded from QuickBooks and then forwarded to someone for review and printing.  The person that printed and presented the report states that they combined two pdf reports into one document and when they were combined, it resulted in a "file corruption" and the discrepancy in the numbers.   I obtained the original electronic file from the person that prepared the report.   The *only* numbers that are different between the original and the one the one when the discrepancy are the totals.  All of the line items stayed the same and there is no difference in any other part of the report.    I don't see any way that the numbers on a PDF file would change in this manner due to a "corrupted" file.  It's not a spreadsheet.  There are no formulas associated with the file.  The only way that the numbers would have changed is if an intentional edit was made.  I have requested an electronic copy of the "corrupted" file.  They have refused to provide it.   If the file was "corrupted", then it wouldn't be viewable.   How can I prove that they are lying to people who do not understand the difference between a PDF and a spreadsheet.