Time of assessment

I would like to find out how long a assessment should take? My granddaughter took her son to his assessment, the clinician was late due to her laptop was not set up. Appointment lasted 20 mins. Granddaughter went armed with videos written evidence etc. This was not looked at. The clinician then said he was just development delay because he could say the types of dinasours. Which is the only thing that interests him. I am a foster parent and have had many children with additional needs. She is deflated as she spent such a long time getting all the information together. As a support assistant herself she knows how important these assessments are.

What us the next step forward?