prestashop 1.5.6.2 / modify mySQL query in OrderInvoice.php to include table ps_product_attribute

Hi there, old prestashop 1.5.6.2 highly tweaked. I need somebody to modify a mySQL query in [login to view URL] to include information from table "ps_product_attribute". In this table the wholesale_price of product combinations is stored. I use a custommade [login to view URL] to generate pdf´s and need the wholesale_price of the combination used instead of the standard (base product) wholesale_price which is stored in table ps_product. I think for somebody who knows what he´s doing it´s a very quick thing, but more work will come and this is a nice little project to get in touch. You will have to work "offline", sending files back and fourth through me cause the shop is up and running, but surely i can provide all necessary info/files/etc to get it done. best Holle