Basically your husband's dispute with this other guy is a CIVIL matter. The other guy claims that your husband owes him money, and if he does, and your husband doesn't pay, then this other guy needs to sue your husband in the Magistrates Court. He will need to run a trial to prove the reasons why your husband owes him the money.
BUT, what this other guy is doing amounts to CRIMINAL conduct. One is not allowed to resort to violence in order to achieve something. The harassment and threatening conduct is criminal in nature. You are advised to report this conduct to the police, and ask the police to open up a case of assault / the threat of assault against this other guys. The law does not permit this other guy to behave like this.
The police might try to argue that it is a civil dispute between the other guy and your husband, and that means that you can't open up a case against this other guy, but the police would be wrong. This other guy is not legally allowed to resort to violence (or the threat of violence) in order to achieve something. You must MAKE the police open up a docket and investigate the assault. You must remember that assault is wide enough to include physical assault, verbal assault, and the threat of assault.
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