SAA - Teenager Left to fend for himself to USA

My Teenage son was booked on SAA flight via Frankfurt to USA as an assisted passenger. Despite confirming during checkin that he would be escorted from the plane in Frankfurt to the SAA Lounge where he would wait 8 hours for his connecting flight before being handed over to the staff of the USA flight he was left to find his way to the lounge where he was denied access (again he showed his ticket that was clearly marked ASSISTED PASSENGER) as he was travelling economy! <br> I have tried to resolve this issue directly with SAA but it appears that they can't be bothered to respond to my complaint privately. This is a major issue as a lot of parents trust the staff of SAA to take care of their children whilst they travel alone, I have used SAA when my son was younger and never had an issue - he was always well taken care of but it appears that the standards have dropped! Child trafficking is in the news with the new laws governing how our children can travel yet SAA staff found it not to be a problem to leave a first time international flyer alone..in a foreign airport after 'promising' to take care of him. We were lucky in this situation that he arrived safely - next person my not be