Not everything responds to holy water and/or faith. Even when I met satan in a dream once, it was a peaceful conversation but I told him "no" when he said he wanted me. Satan will walk away sometimes but many of his demons will straight up kill you if you try to get rid of them.Have you listened in to the Beyond Darkness from last week on these entities? Also, Heidi Hollis is one of the experts on this so do check out her website.
I have yet to find a way to be rid of one that has followed my son for 35 years now. They are thought to perhaps be Djinn, which is why they don't respond to Holy Water, etc.
It's been a while since I picked up a Quran but from what I understand, satan is a djinn according to Islam. But usually they are seriously deformed creatures. Imagine a failed lab experiment chanting "kill me". I've seen djinn in my dreams. They don't look like men . Any Muslims on this forum that could elaborate and possibly correct me if I'm not explaining this right?