The Anti-Social Behaviour, Crime and Policing Act 2014 introduced the Community Trigger which is a process that victims and communities can use to ask agencies to deal with persistent anti-social behaviour. Please see here for details.
Report anti-social behaviour via the Community Trigger here
Report incidents to Essex Police here.
You are welcome to bring your dog to King George V Playing Field, however please keep them under control and clear up after them in the bins provided.