I didn’t know congress critters had the authority to arrest people.
There is a lot you and I don't know.
Congress has the authority to force testimony and they have the authority to arrest and hold those they find in contempt, they just haven't chosen to do it.
This is where inherent contempt comes in. From the Republic’s earliest days, Congress has had the right to hold recalcitrant witnesses in contempt — and even imprison them — all by itself. In 1795, shortly after the Constitution was ratified, the House ordered its sergeant at arms to arrest and detain two men accused of trying to bribe members of Congress. The House held a trial and convicted one of them.Congress Has a Way of Making Witnesses Speak: Its Own Jail