I would like to terminate my account and all services due to there's a big problem. ..

My old sister (63) is stalking me, harassing me, cyber bullying me, etc.  It creeps me out so much.  When you look at the time span and all the posts that my sister Kelly did on my individual account., it's bizarre to say the least.   It's going on 20 years now that this loser will not get a life of her own.  I know that Xfinity will not help me.  I'm trying to find out information that I received regarding phones that I purchased on payment plans.  Of course this would be fraud from my loser sister.  To me, there's no point, but some people have to know every single thing you're doing at every single moment in time.  My sister will have her time in prison hopefully sooner than later.  Does cyber security even exist?  Because you would think that I could get some kind of help from Xfinity.  Their BOT not mine.