hair weaving

`As-Salamu `alaykum wa Rahmatullahi wa Barakatuh! Is hair weaving permissible? I heard that it is haram. But a bald-headed friend of mine has done it. He said he paid a lot of money for what he called weaving or stitching hair. But now, after being informed by many people that it’s haram, he feels confused about what to do next. Please clarify it. Jazakallah kahyran!