URL Rewrite

[Gipielle]

I have my own url link that i want to use for the products, (categories are not important right now). The links are made in the following way:

product-xyz-p-number.html

where -p- is always present, the number is not correlate to prestashop product id.

So i want the urls like:

www.misite.com/product-xyz-p-number.html

The htaccess is the default one, i tried to modify classes/Link.php by removing language, category and id's and keeping only link_rewrite.
On the categories page the link is still the old one ( lang/categories/id-link.html ), but when i click on the pruduct link i get:

www.misite.com/IDproduct-xyz-p-number.html
where ID is prestashop product id

What sould I do to get the link as I want ?

Thank you so nuch for any help you can give me.