I've been getting numerous messages from simpleescorts clients now, it seems that their 'booking' system automatically sends off a text that links to the stolen profile when a client tries to contact me. I'm considering just taking over the profile myself, if they have given me a premium listing maybe I should take advantage of it?

I would send a second email.
To write an email I would use AI (Gemini or whatever) to make it neat and limit the time spent on dealing with these arseholes (a prompt along the line - "Write a strongly-worded email telling the website owners to remove my details and content that they stole from my advertising. Quote UK and USA copywriting laws as well as trafficking. Threaten with legal action if not removed within 2 business days.")

Looks like they are using Cloudflare, so include in the email that you will be filing a formal complaint with Cloudflare.com