For anyone that has been dunned by a cyberstalker, some details for you...  

Cyberstalking is a Federal crime. A person convicted of stalking under federal law faces a possible prison sentence not to exceed 5 years, a fine not to exceed $250,000, or both (18 USC § § 2261, 3571.) PER OCCURRENCE. Where the defendant’s stalking conduct results in the death of or physical injury to another person, a conviction may lead to a sentence of up to life in prison.
All anyone has to do is file a complaint with the FCC and present all the evidence you have been saving. This could be snapshots, screenshots, video, or other court-presentable electronic methods. Be sure to capture the date (if possible, otherwise the metadata on the captured photo will have to be used) and the avatar and handle of the person posting the offending content. Better yet is to use a service like Archive.today or the National archives Wayback Machine and archive the ENTIRE thread. Be sure to bookmark it and/or download it in PDF format for safekeeping (see this post as to how: https://www.digitaltrends.com/computing/how-to-save-a-webpage-as-a-pdf/ [archive: https://archive.vn/frjvv]).
The social media platform will have the stalker's URL and can easily identify the stalker(s). Should they be using a VPN, the provider can be notified by the social media platform of the actions of one [or several] of their account owners - VPN providers do not take kindly to cyberstalkers either.
Be sure to know who your witnesses are and keep all your documentation in a file offline and not on your computer. Be sure to keep several backups in different locations as well (best practices).

To report a cyberstalker in the U.S., go to: https://www.fightcyberstalking.org/

Most countries already have protections set up, search for "<your country> cyberstalking" for resources to consider - and be sure to share with your social media network(s) if you have a cyberstalker that loves proving he or she is as dumb as a sack of hammers by reappearing on your account and/or your followers' accounts.