Oscommerce PHP Add Free Gifts

Using OSCommerce, I need a function which will add free gifts to an order depending on the criteria which may be : Buy xx items from this category Buy xx items from this manufacturer Spend xx in this category Spend xx for this manufacturer Buy xx items with a min spend of xx from this category Buy xx items with a min spend of xx from this manufacturer I have ALREADY got the admin page and the database table where these free gift options can be added. What is needed is the shopping cart function to check what is in the cart, whether it matches any free gift promotions and if so, automatically add it with a different css style so it will stand out. If any products are removed from the basket which makes the gift offer invalid, then the free gift must be removed. To work on this, you will need a vanilla copy of oscommerce. I will send you the admin page and the database table details. You will not need access to my system. I will try to add the files to the project clarification board, if I cannot do that then please request for me to PM them to you. It is probably best that you see the admin side so you understand what this project entails before you bid. Price is open to negotiation. If you undertake this job, I will NOT spend time on any private chat with you unless it is vitally needed. It is expected that you will be able to see and understand what needs doing from the files and my explanation here. If you feel you might not understand and need more clarification then please ask before you place a bid or accept an offer.