Aggressive and unprofessional bullying hotline operator

I have just had a 5 minute call with someone on a supposed 'helpline'. The person concerned was aggressive, unprofessional and left me shaken. They also talked about autistic people as 'they' at one point making a really offensive comment. I was barely able to get a word in and within 5 minutes was told I was in denial and was wrapping my child in cottonwool. I am still astounded at the verbal attack I experienced. From some quick googling I see that this person has a record of intimidation, unprofessional behaviour and ironically bullying behaviour.

Who can I complain to - more because I would hate anyone, especially someone who is vulnerable to be verbally attacked in this way.