Cant get courtesy car because an Kenyan

Had an accident on Friday night and through my insurance, I was told to go to Avis Sandton to get a courtesy car. I meet the rudest of staff who gives me a piece of paper to sign without even explaining what it was that I was signing. Anyway, i do that and on presentation of my international DL, the same licence i use when travelling, when stopped by cops, same licence accepted by my insurance when I app**** for finance for my car, basically the same driving license i have been told i should use is not accepted by Avis. What nonsense is this. long story short, i leave without a courtesy car and am left wondering, whose story should i believe? Avis or the law that stipulates that i could use my international DL legally in SA.