What do you mean by "corn substrate"? Are you talking about ground corn cob? That stuff is nasty! The slightest moisture and it is teeming with bacteria and fungus!
As for the mites, I have no idea what products would be available in Africa!
I know that people have used human lice products but I have no experience with that.
Have you asked your vet for a recommendation.
You won't see the mite eggs with the naked eye.

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Merlin,
What's Life Without A Little Magic!

We have removed the ground corn substrate and replaced it with news paper.we have spoken to the vet and they did recommend a few things. The problem here in SA is that to buy their products we might aswell buy a new boa considering the prices.
I have found something on the net called ivermec(tin)
The vet said that we can use it to get rid of the mights and the eggs but they are not 100 percent sure of it as they have never used it, they did do some homework on it but they are not taking responsibility over it....... Is there anyone who has used it and succeeded with it
PLEASE HELP!!!!