Hi, I am not sure that I understand the process that you are in for getting mental health care. Maybe this is the UK system? However, in my view, you should NOT be dismissed by a psychiatrist or any doctor for respectfully getting a second opinion. That is the patient's legal right (at least in the US). It sounds like these people are very into labeling you, rather than helping you.
If you have to go through your current system to get mental health care in the UK, then I would definitely go to a higher level of authority within that system until you are able to meet with someone who can help you resolve the problem and get you an appointment with a professional who can care for your mental health needs. Is there a patient advocate in that system who could help you? Or could a family member or friend or an attorney represent you in dealing with this system? It can be hard to deal with these systems, especially when you are feeling vulnerable already.
It may also help to write down what happened in a very calm, objective, businesslike manner and have that available for when you meet with someone. Or send it as a letter to someone at a higher level of management in this system who hopefully can address the concerns.
If it is possible for you to get private care outside of that system or to go elsewhere, I would encourage you to strongly consider that. It may be easiest to just find a new professional with whom you can work well and forget all of this other stuff.
So sorry you are going thru this experience. M