Find duplicates, concatenate into different column, sum and delete duplicates

I have 3 columns, second column have duplicate value, third column have numbers. If duplicated found on second column, I need to concatenate the third column into the
first duplicate found across different columns. Then sum at the last column and delete all duplicate. Somtimes my file have over 200,000 rows.

Example:
col A col B col C
ISA ABC 235
ISB ABC 123
ISC BCD 6756
ISD BCD 5647
ISA CDE 1234
ISB CDE 6537
ISC CDE 675
ISA CDE 4536
ISB CDE 67537

Final result should look like this:
col A col B col C col D col E col F col G total
ISA ABC 235 123 358
ISC BCD 6756 5647 12403
ISA CDE 1234 6537 673 4536 67537 80517


Many thanks