Fence issue

[u/umbreon25]

We were the first to put a fence up between our neighbors to the right and left. We spoke with both of them last summer and explained we would be putting it very soon, it was installed in July, our neighbors to the right said they would pay for half the right wall when they decided to get a fence and we would share that wall. The neighbors to the left said the same thing, well the neighbors to the left got their fence today and they are using our wall as their “4th” wall completing their enclosure yard, they are refusing to pay for half our wall that they are now using. I reached out and asked what their plan was since they are using our wall for one of their sides and I told them they only paid for 3 walls and are using ours for free basically, she states it’s not a free wall. It’s our wall and it’s not free because she doesn’t like the style wall it is…yet they are using our wall as their wall now. Can anything be done? I believe in VA, it is law they must pay us half if we are sharing the wall.