"Audiologist assistant said "Stupid boy" to my..."

My 2 yr 1 month old son recently attended a hearing test at the Phoenix centre as he is now being monitored under a paediatrician there for Autism (Social communication disorder), so part of that is ruling out any hearing issues, he had previously had glue ear and grommets fitting privately, so this was our first experience of the audiologists at the Phoenix. My son struggles with communication and understanding instruction, as he didn't understand the audiologists assistant who was trying to get him to sit still and play with the toys appropriately follow her instruction, my son likes to collect toys and will not share them (all part of why we were there). She said "stupid boy!" when he wouldn't follow her instructions, I was so taken back, I thought to myself - did i actually hear that correctly!! Yes I did but was too taken back at the time to say anything and the other Audiologist didn't say anything, so I suspect this didn't come as any surprise to him. My son is far from "Stupid" he is a clever little boy that does suffer from a SCD, I know that, and that's why we were there and I am deeply sadden and shocked at what i heard. I really think there needs to be more awareness and compassion for young children struggling with communication and other issues that may not be obvious by the naked eye. If his disabilities had been obvious to her, i'm sure she would never have called him a "Stupid boy". It has upset me deeply, and over the last few days has been on mind and has made me realise what my son will experience in his life because of his difficulties with communication. It's not acceptable.