Get code involved... if the violations are as serious as you are saying.. it sounds like code will have a field day.

IANAL. I am the child of a hoarder.

It will not be this simple. Yes, call code enforcement but they will not just roll up and fix the problem. This stuff takes time and persistence.

My parents are hoarders. Code enforcement was at our house regularly. They wrote warnings. My dad looked up the laws and complied to the letter. Example: code enforcement warned about a pile of random junk. If the ordinance said that random pile of junk had to be 3 inches off the ground and covered in tarps then he built platforms, put junk on platforms, covered it in tarps.

Some ordinances are harder to evade than others. Things like grass, anything they requires items to be in the back of the house, etc. Keep calling about those first.