once a professional, always a professional.
if your client requests a service that you have doubts may be suitable or correct for him/her, recommend the service that you know is is the client's best interest.
if the client insists on having the service and you feel after the consultation that the client is still unable to understand the implications of what he/she is asking, seek support from your manager or owner.
if the service is still requested, please ensure that the client signs a release form.