Bullying from Airlink staff

I travel all the time as I'm a professional private guide that take Americans through Africa. I got harassed by Airlink staff at Cape Town Airport recently when I had to fly back to Botswana where I live. As I was checking in for my flight a woman appeared and quite rudely started to interrogate me. She demanded my permit to stay in Botswana. I presented her with my official papers from Botswana immigration which she declined. I am allowed to legally stay in Botswana as I'm assisting the police with a ******** investigation, this is clearly stated on my immigration document. She said I can't board my flight unless I have a return ticket. I actually live in Botswana, I have a life in Botswana. My car, my camper and belongings are in Botswana where i live. I had to get back to Botswana as I had to meet new clients that arrived from America, so to refuse me will have serious consequences as it means clients that paid for a very expensive holiday and guide would show up at Maun Airport with their private guide nowhere in sight. She refused my permission document to live in Botswana. Luckily I had a next flight booked to return to Cape Town on a next tour I was guiding in SA. She seemed terribly disappointed when I showed her my booked flight, almost like she was targeting me and wanted to get a kick out of refusing me to board. I felt brutally harassed and embarrassed as bystanders were watching. I reported the incident as I need to make sure this doesn't happen on my next flight. It has now been more than two weeks that a certain Nonhlanhla Hlanguza, a customer care supervisor, is investigating. A Nkululeko Mnguni, a customer care agent, is also investigating. Yesterday I emailed Mr. Hlanguza to follow up as I have to fly to SA and back to Botswana again shortly, so I followed up as I want Airlink to give me some reassurance that I won't be harassed again and possibly refused a flight when I in fact have legal permission to live in Botswana. I'm not getting solid feedback, only that the investigation is ongoing and that Airlink is not fami**** with my documents. It feels like the situation is only getting dragged out by asking questions like, do I have a valid passport. Seriously, I just travelled internationally, obviously I have a valid passport. I need answers so I can be certain I won't get harassed again and embarrassed publicly by Airlink staff when I have done nothing wrong and have legal papers to live in Botswana. My company has spent millions on Airlink in the past 15 years as we book many flights through our agent to transport our guides and clients in Africa. I feel so let down by this treatment. How do one stand up against this when you are perfectly in the right, but non caring, non compassionate, angry people target you? I would appreciate solid feedback and a resolution to this issue to avoid very expensive mishaps. This is negative for tourism, especially when clients are traveling with a guide.