Index/Match, SUMIFS or something else? NEED HELP!

I need to create a formula that will give me a total sum of data in specific columns after searching for specific identifiers in a specific row based on an ID.

Basically I am entering up to 500 clients TBs into a spreadsheet. I want to group them into like accts then create a sum of those groupings. I need to be able to quickly grab that data based on an ID I enter into A1. So it will need to search for the appropriate column for the grouping label then another column for the totals, all based on the ID I entered.


I've attached an example of what I need it to do and be somewhat laid out. This is rough right now so might need to be tweaked or moved around so need something somewhat adjustable.

And if I don't have to label the columns "grp" with ID or "Acc" with ID I am fine with that...its the only way I could think to search for the correct column

Thanks