Turkish Airlines Employees at Istanbul Airport - Special Needs Assistance Issue

Hello. I bought a ticket from London to Istanbul. On my way, the lady in charge of baggage handling was very helpful because my son has special needs. She even sent my hand luggage directly to the plane and advised me to get a special card to hang around my son's neck, which would give us priority everywhere. This made our journey very comfortable. However, on the return trip at Istanbul airport, I waited for half an hour with 30+30 checked baggage and two cabin bags, only to find out I was directed to the wrong place. I had to take my belongings back to the car and barely made it to the correct location in time. When I told the gentleman handling the baggage about my son's condition, he was not aware of the card and even implied I was lying. Later, I asked the lady weighing the baggage about priority, and she not only didn't know about it but also caused issues with the baggage. Normally, every time I fly, even my cabin baggage is taken care of. If the same procedure is valid in London, why isn't it in Istanbul? Creating such difficulties for people instead of helping them does not benefit a large company like THY at all.