Scheduling vehicles for service

We allow our deputies/clients to schedule their units for service. It would be great if the deputies/client could schedule their units for service on a day that works for them. Fleet would still control the number of services per day, but the person scheduling their unit could email in and pick from available days to put their unit on our maintenance schedule. After the service is updated by fleet, then an automatic email could be sent telling the deputy/client that the repairs to their unit is completed.