Interesting,thanks all of you who replied.
I think that you're 100% correct LOKI,trusting your ears can be dangerous! thats how "Transavia" became "Tanzania"! To be fair,there was a huge amount of t/storm static so it couldn't have been more than strength 3 on thr RT.
REJ also makes a valid point,i often hear odd three letter codes such as VDA or ADB or WBD,all belonging to airlines with callsigns,being used instead of the proper callsign.This is in Joburg airspace as well as north of us into africa.A notorious case is MK Airlines,who almost never use their callsign "Kruger"...i doubt many people even know that its their callsign! i think i've heard it used twice and i'm very often on frequency when they are coming in or out of here.same goes for SBO being used in place of "Stabo" for some of their freighter flights.