Contact PlotNest
The quickest route depends on what needs fixing.
A mistake in movie or TV data
Synopses, dates, runtimes, credits, images and scores come from TMDB. Anyone with a free TMDB account can propose a correction there, and PlotNest shows the updated information automatically, usually within a day. Streaming listings come from JustWatch through TMDB and update the same way.
Anything about PlotNest itself
A contact address has not been published yet. PlotNest would rather list nothing than offer an inbox nobody reads, so a working address will appear here as soon as one is set up. Meanwhile, corrections made on TMDB fix most data problems.
Things PlotNest cannot help with
PlotNest does not sell subscriptions or play video, so it cannot help with accounts, billing or playback on any streaming service. Please contact that service directly.