If the aircraft fly in and out of South Africa then it will not be that hard, if its in the DRC you are
.
If the amount is under ZAR 50,000 could have gone up you go to the Magistrates Court (easier with a lawyer) get a hearing and a default judgement in your favor will be issued.
Then you have to make sure it gets to the Sherrif quickly so when the aircraft is on the ground you can have it blocked from flying.
ATNS can do nothing, they can only act on a order from the court. With lawyers it works this way:
Cheap ones are good golf buddies and will cost you ten times more in the end.
Top guys will break arms and legs as long as you can pay them. But if you can attach the aircraft you will be ok