there is not an option in the in-world report system that covers this. you can send a PM here on the forums to HomeForumMods.
Include the time, what time zone you are in, the space you were in, who else was there, who you suspect of freezing, why you suspect it was them, etc. as much detail as you can remember.
Thank you for not posting the details here, as this is a matter for Moderation to handle.