OP, the key point is that you are a volunteer, and you can cease volunteering. You appear to have experienced an instance of a sector which is in crisis after years of underfunding of public resources. CABs and other agencies struggle to deal with an array of societal problems which have been exacerbated by the withdrawal of State provision in many contexts.
Universities are aware that it is difficult for applicants to obtain relevant work experience, and therefore they don't regard such experience as essential when considering applications for places. In any event, you can now truthfully say that you have volunteered at a CAB.
I agree with Crazy Jamie, who is an experienced barrister, that labels such as "toxic working environment" are not helpful. Working through internet checklists to find a match to your situation is also, I suggest, unhelpful. Your particular experience is your own, and when taking advice it's best to listen to an objective adviser such as Crazy Jamie rather than someone without comparable experience, who might be transposing their own perceptions of grievance onto your position.
I suggest that you cease volunteering at the CAB. If you wish to volunteer at another agency, do so. Or focus on your studies for the time being. Making complaints would simply add to the pressures already faced by people working under considerable stress, and to little or no good purpose.