Hi @Shelley474
I'm a Bristol host too.
No you can't report them . If you want to limit your heating you need to make this clear in your listing and in your house rules that there is a heating limit
They do sound difficult guests.
just make sure you've properly costed in likely gas and electricity bills into your winter rates . Some guests use a lot , some very little.
You could mention in your review that despite the unseasonal y warm weather for a UK autumn the guests had the heating on for up to 28c during their stay but still raised concerns about being cold.