Use a reputable company like Budget or Hertz. Also, inspect the car for any damage before taking it away, and point any marks or scratches out to them as well. Take a photo too.
If you take the same precautions as back home, (valuables out of sight, make sure its locked, etc) Patong is no worse than anywhere else for theft from cars.
Can't help you with jeeps, but I think all companies below hire them out.
https://www.hertz.com/rentacar/index...Homepage.j sp
https://www.avis.com/AvisWeb/home/AvisHome
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