Tree Roots

My neighbor has 5 trees in her back yard. I have TRIED to speak with her on several occasions about her limbs hanging over my fence. My self and my husband had previously trimmed them on several occasions but we are both on disability and can no longer do this. At the same time I have tried to speak with her about the limbs I also needed to talk to her about the roots of these trees up rooting my retaining wall and causing it to lean along with my privacy fence. Every time I have tried to talk with her she says "i'm calling a contractor" The walks away quickly. This way she has no idea what I need to speak with her about on the trees. I have gotten many bids on this and the smallest on is $19,000 this is how much damage is contiuing to happen to my property. I have massive photos that show the roots on top of the ground on her side and then going under my retaining wall. This is not visible from our side of the fence. I also have many photos which do not have to do with my damages but iare health hazards, just to show her consistency of neglect. Ihave sent her 2 certified letters and 2 direct mail letters informing her of the damages. The second set of letters was very explanatory. I have been requesting her insurance co. but she has negected to speak to me or respond to my letters. What's next.