The VA may have spent more than $256 million more than necessary for the purchase of prosthetics in fiscal 2015 alone by using government-issued purchase cards rather than contracts, an IG audit has said.

Extensive use of the cards, which are designed for smaller purchases–limits that were exceeded without required approval–meant that the agency “did not leverage its purchasing power” and “failed to ensure fair and reasonable prices,” a report said.

This occurred because the office of prosthetic and sensory aids didn’t identify commonly used prosthetics, and the procurement and logistics office did not adequately monitor procurement practices, it said.

It recommended that the VA review all commonly used prosthetics offering opportunities and pursue appropriate contracts, conduct annual reviews, and “consider holding cardholders and their approving officials accountable for unauthorized commitments, as appropriate.”