@Trust 789
bemechilas kevodach you are incorrect. being mechalel shabbos definitely affects a persons neshoma albeit in a different way. Every aveira creates a stain on a persons neshama. People seem to go way overboard on the concept of metamtem haleiv – it is an issue but not an overriding one to the point where a person can not do teshuva from it. There is no such a thing called internet addiction. The addiction you are referring to (I am assuming) is of a different variety vhamayvin yavin. Yes it is doable but a person requires the motivation. The most important thing as I mentioned before is not to tell the person that he is a hopeless case and to make the person happy with small steps if that is what he can do. It is doable and many have successfully controlled it before. A mentor/rav is crucial in this situation.