If true (Congress should investigate) then Congress should use the budget to destroy the FBI as it now exists and divide it into a number of different functions with extremely limited authority to investigate political figures and divide the current agency over at least a dozen other agencies. The new enabling laws should also require that current political appointees are not allowed to apply to the new agencies.
The FISA court should also be overhauled.
I don’t believe there is anything the FBI does that can’t be handled by the State AGs. The federal role could be reduced to coordination of effort.