Booking has other issues too. all these sites actually run on almost zero employees since covid. so there is no one to take care of any issue and sort it out.
booking still has listed hundreds of hotels and hostels which closed long back. they take the money and keep it.
go to the police quietly. tell them everything. show them a video/ call recording. call her from police station to reconfirm. lodge official complaint. take the police with you to her place only after complaint is lodged. keep a local with you to understand whats being discussed.
there is nothing purely vegetarian in Thai food. so even if the menu shows something, they will use the same cookware as others. also they will us the same sauces like fish sauce and fish oil. try vegan restaurants. thats ur only option