Send in the US Marshall’s to confiscate ALL the documents
The US Marshals are part of the DOJ. They work for AG Sessions, who works for POTUS. In cases like this, POTUS either supports his AG and tells congress to pound sand, or he directs compliance. Failure to follow the order of POTUS would result in firing. Unfortunately, we are now living in bizzarro world, and the POTUS appears to have no authority over his own DOJ.