Hi,
Since this is custom modifications, you are on your own to do these edits. Our free support service doesn't include any kind of custom modifications.
The PHP file you need to make edit is this:
ROOT/templates/<yourjoomlatemplate>/html/com_virtuemart/productdetails/default.php
(default.php, flexv2.php or what ever product details page layout you are using)
Then you can change the order of the TABS from this page. Basically only little HTML knlowledge is enough to achieve what you are looking for, you will change the <li>....</li> orders in the footerTABS section.
Cheers.