I do not believe that. You might have gotten the wrong one. Try emailing back. I'm 95% sure they hand histories are stored on the server, they don't come from the user's device/computer. If what this rep said is true, you could edit an hh and then complain that you didn't get the right money.
One thing I have seen is that they tend to have a break in the top line that just needs to be deleted so it looks like the normal HH's.
Ask for your tournament summaries as well. They need to be saved on your computer as well.
Sites like Poker Stars, Full Tilt Poker
and Pacific will require a separate Tournament Summary/History file to be imported for HM2 to properly calculate the size, places, and prizes. If your site does not write summaries, or you experience any discrepancies with the results, you will need to manually edit the results via the Reports > Tournament > Tournaments > right-click > edit.
You may need to request and import any/all of your old tournament histories and import those to HM2. By default Stars do not write the tourney summaries to your hard drive, so please enable the option in the PokerStars client and be sure that HM2 has added the folder to your Auto Import Folder Configuration.
Email support@[yourpokersite].com and ask for ALL your old Hand Histories and Tournament Histories/Summaries.
They will send you an email with links to zip files of your hand histories. Download all the zip files. Right-Click > Extract the contents of each zip file to a new folder. HM > Import From Folder for all of the unzipped hands.
The tournament summaries may be attached to the email as .htm files. Download the attachments. HM > Import File(s) for all of those files. It will probably ask you to search/select your Pokerstars screen name. If the files are sent as .html you will need to rename them (Right-Click > Rename) from .html to .htm extensions.
Example of correct file:
If you continue to have problems, please zip and email the problem hand histories. All original hands that are auto-imported get moved to an archive for performance reasons. Your \HM2Archive is in C:\HM2Archive by default, but you may have put it anywhere. The archive should be organized by \Month\DayOfMonth (example: D:\HMArchive\2009\07\31).