Index and match function for same item in the table

[ronlau123]

Dear all,

I have a excel sheet with table. For actual file, it has more than 300 account manager's sales data.

I use index and match formula function, therefore, I don't need to use find and search.
However, for certain account manager, they change from team 1 to team 2. My boss would like to combine two data of same account manager.
How can I modify the following formula to complete tasks?

=INDEX($C4:$D9999,MATCH($B17,$A$4:$A$999,0),MATCH($D$16,$C$3:$D$3,0)

C4 is account manager, David.

I have attached the excel file for reference, thanks