"No assessment in A & E"

I had to be taken into A&E due to my mental health deteriorating.  I waited as expected and then told by the Doctor that he was quite new to the  hospital and was going to speak to Mental Health on the telephone and see what they thought about assessing me.  I was crying and distressed.  The doctor came back to me and said another doctor had advised there was no need for me to be seen and I was asked to go home.

I was quite taken aback but did not know how to express this at the time.  To find out later down the path that an outpatient team could have seen me was very alarming.  What was happening here and why was I not assessed at a very turbulent time and how could a doctor make such a quick decision over the phone without any assessment of me?

I would like a reply and really just an explanation.  Surely Mental health is as complex as General health and deserves to be investigated?