Black hat SEO techniques are mostly adopted by people who want the changes in SERPs very quickly and for short period of time. But these are spam techniques and Black hat SEO providers often fail to notify the client that they use spam techniques to
Increasing SEO is a game of patience. You are not going to realize a major change in your traffic overnight. It can take a lot of time if you are new to this. It is no different than having a brick and mortar store.