It's something that can have a multitude of different opinions. And often those labeled with mental health issues, are instantly thought to have an added mental health issue as soon as hallucinations arrise. While that can be exactly what these are... there are other opinions and other ideas that would/could state differently...
Sometimes meds can actually cause issues, so the question might be, have you started or stopped any meds recently(depending on what type of med, and how long it was previously taken for, could contribute to how long the withdrawl effect could last)(if that's what it is). You're age may play a factor in this as well.. like if you were in the general age range of those who end up with brain changes that can cause symptoms like these...

Have you had a neurologist to talk to about this? there may be some tests he/she can run to rule out any tumors or sezures or sleep issues or other related things, that could be presenting itself by hallucinations...
Is it pretty much a constant link of communication between them? when this happens, does your grasp on reality start to bend, or change? and then do you regain the grasp of reality between when this isn't happening?

However, if its no hallucinations, and if it's some sort of psychic related connection... Just know, that they hold control over people by fear... if you are no longer scared of them, they have no control, and will eventually leave you alone.
Also, telling them in a direct and powerful tone to leave you alone, and that you dont want them around you anymore, and that you no longer fear them/and they no longer have any control. and if they dont leave you alone, that you will have someone banish them, leaving you unharmed. And that you will no longer listen to them, and will ignore them if they continue to invade on your space, and that you have reclaimed your space back, and it is no longer open for them to ever use again. and "leave now" - I have heard this helps.