1. Can you accept that data (as in Data Sheet) are arranged another way than shown (vertically instead of horizontally).

2. What kind of dates (in Data Sheet row 11) are we talking about. I wonder which year was 1 January a Monday. Can we use real Excel dates instead of strings like "Monday January 1st.

3. For how many weeks will there be data.

4. Will it be necessary to distinguish between shops (It doesn't seem so in your Summary Sheet).

5. Can you accept a pivot table or must it be a formula solution?