Count filtered items

Hello everyone,
I'm really not sure if you will understand my question or not becuase it is very hard to explain, but I'll give it a shot.

We are making products which has two parts, PART A & PART B. If both the Parts are purchased by the same individual we take it as one product and allocate a unique ID (Product ID) given to that product. So if Mr. A buys both the parts, we will say

Product ID - Part
1 - A
1 - B

If a customer busy one part only we still take it as a product and note which part of the product has been purchased. Say Mr. B buys Part B only, we will say.

Product ID - Part
2 - A

And then all the products & Parts are borken into Phases.

Based on the conept, I would like to have help in developing a formula for:
E5 to E8
I5 to I8
K5 to K8
M5 to M8
O5 to O8

I've attached the table in the .doc format when its taken in excell the table is perfectly placed. Thank you for your help, in advance.