We started an online business where we gave somebody 10% free shares in exchange for marketing services. For the first 6 months of his involvement it was a struggle to get him to do any marketing whatsoever. He offered his student son to provide some technical services for roughly 2 days per week. We warned him before starting his son's services that we do not have money to pay for his services and if he needed payment then we will not be able to provide. He stated that we should not worry he's got to pay his son anyway and he will remunerate his son as part of the deal. Unfortunately we had no written agreements to that effect. After about 6 months, when pressured to do marketing he went into a rage and walked out of the business. The next we heard of him was an exorbitant invoice for his and his son's time, travelling and toll fees over the 6 month period. We rejected the invoice and tried to reason to no avail. All he was interested in was payment and threatening us with bodily and property harm. We paid a lawyer for commercial litigation to write him a letter to stop the threats and to come forward and state his case, which he simply ignored. Subsequently, not being able to close the business he was a shareholder to and not knowing what to do we started another business providing the same services(with clients he had no part to); which he is now targeting our clients on Facebook with posts saying that we are "dodgy" operators and trading an illegal company. Does anybody have some advice as to what we can do about it under commercial law? We are a new business struggling to keep head above water -never mind having to cope with expensive lawyer fees (which he ignores!) and false accusations and defamation potentially causing damage to our new and potential clients. Did anybody else have this ridiculous experience and what can we possibly do?