We recently changed providers, after several complaints from staff that the existing service had not met their needs. They had cancelled and changed appointments at the last minute, and then not handled the complaint well.
The change process involved reference checks with other clients of the provider, as well as interviewing the providers to determine their processes and capabilities around service provision and complaint handling. But it is a difficult call to make due to the confidential nature of the service being provided.
However, we are very happy with the new service and the staff feedback that we have had has been good.