Selecting and Summing Date Values

Hi guys,

I have an excel sheet (see attached) that i will be pasting columns A to G in every month. What i need to do is for Excel to

1. Automatically provide a unique list of Approver ID (i can already do this with Advanced Filter)
2. Count how many of this unique entry there is (can do this already)
3. Then to find and sum all the time differences for that approver so a total approval time taken time is outputted for each person.

Any help is appreciated!