Tree Removal 

Recently our neighbor has had the property line surveyed and after this has been done we have found out a very large tree that has been hanging on the roof of our garage is clearly on her property.  We have tried to work with this neighbor in the past to have this tree trimmed or removed at our cost but she refuses to let anyone on her property with equipment.  Our property is completely fenced in with a chain link fence and there is not way to access the tree from our property.  After the survey we requested she have the tree trimmed and removed off the roof of our garage.  She is refusing of course and stating that it is our responsibility to have it trimmed.   She sent me a letter in the mail stating this.  I have checked on city ordinances and also asked one lawyer that states this is her responsibility and should be done at her cost.  Do you have any advice or what can I provide her with as documentation stating these needs to be done by her at her expense.  Thanks