Poor performance or attitude should not be tolerated. Where poor performance is evident work with the student to ensure they are aware of your concerns and try to establish the root cause of the problem. There may be issues outside of the placement impacting on the student. Work with the student to identify how to remediate the issue/s. Adjust their learning contract if required.
Contact the education provider if you continue to be concerned. In extreme cases the supervisor may need to terminate the placement and this will need to be done in conjunction with the education provider.