Failing the same IPC audit points repeatedly — what actually worked for you?

Our last two IPC audits have flagged the same issues: sharps disposal in one clinical room and hand hygiene compliance. We've had the training, we've put up posters, but certain clinicians just don't follow protocol consistently. What has actually worked for others to change behaviour rather than just document the failure? I'm running out of ideas that don't feel like I'm treating adults like children.