Excel 2007 : Formula Needed to change sequence of numbers with different conditions.

I have three categories which are; C2:C16 - Product Category, D2:D16 - Product secondary category, E2:E16 - Required Packaging and F2:F16 - Unique Code, for each product. Basically when I input say, "Book" into Product category (D2), "Educational" into secondary category (E2) then, at the moment I have to manually change the unique code, which I would like this to do automatically however, it's "01-1-01" in this example.

This then produces a product code for me " BK#1~8#ED#PAP#01-1-01 ". However, I can't seem to get the unique code to change in the way I need. The unique code in the product code above is "01-1-01". The first "01" is overall Product 01, meaning it's the first product to the list, I would need this to change to 02 in the next box, then 03, and so on. The second number in above sequence, "1" tells me it's category 1 - Book. So when Book is selected in Product Category (D2) the unique code should automatically enter "1" after the over-all product num, being; "01-1" so far. Then finally the last "01" tells me it's product 01 of books, which should change to 02 when Book is selected once again entered into Product Category (D3). So if D3 is also Books, the unique code should be... Overall product - 02, Book Category - 1, and it's product 02 of books - "02-1-02" I would need to set this up for all the different categories I have amongst Book such as, DVDs, **'s, Furniture etc... Although I can adapt this once I know the code to change sequence for books. Any help would be very much appreciated! I'm getting a headache =(