I understand exactly how you feel. I think parents of children who have send have no idea what actually happens in schools. That only ONE person in a WHOLE school has to have ANY qualifications in additional needs(and even then it only applies to SENCos that started after 2008). In fact they only have to get some training three years after they started the job( 2015 Code of Practice). That the Carter Review in 2015 found that there was virtually no training in supporting children with special educational needs on new teacher training courses. Also in independent and special schools ANYONE can be the SENCo and that they never need to get any training at all.
www.specialeducationalneeds.co.uk/uploads/1/1/4/6/11463509/senco_-_key_information_guide__3.pdf
I would recommend that any parent, before allowing their child to join a new school, should check does the SENCo have the NASEN level 7 award or a masters degree in specifically special educational needs for young people or something similar.
Please, please check that the people looking after your child who might need specialist, trained support is qualified to do so.