wholesaler puts up sign on my fence!

[Luke H.]

Merry Holidays everyone, hope all is well.

I purchased a rental years ago and put a fence up on the property line.  A few months ago the neighbors sold their house to a wholesaler.  This Wholesaler put a banner sign ( 6' x 4') on the fence, been there for a while. I called the number and asked them to remove it,  they mentioned that it was on the property line. 

Anyone have ideas on how the law would play out in this situation? Or what the best way(s) to get them to remove it would be? 

Any ideas @Andrew Pennick? 

Thanks