Agree with Yoda and CheshireCat. This social worker must have a supervisor you can speak to. It may not be the system as a whole, it might just be this one very incompetent worker. The supervisor should be able to appreciate the fact that your mental state has suffered for no other reason than not being able to get hold of the one person who seems to be the gate keeper to the services you need. Tell him/her all that you've told us about the attempts at connecting with the social worker, the responses given, no follow up, and how services as an adult have deviated from your discharge plan.