hey Drak as stated in Conan Exiles Community Guidelines - please read it is forbidden to undermesh and in so you are allowed to send a private message ( the nicer it is the fastest you will get an answer 
) to a funcom community manager here on the forums , also you need to include as much screenshot as proof of your saying as you can , the best would be to take a screen of all illegal structures and also giving them the precise server / server region and if it is a pvp , pve-c or pve type , all the information you can give them will faster the process !
here is how to report a bug How to be a pro PC bug hunter (PLEASE READ)
here is how to report an exploit Found an Exploit? Here's how to report it!