My neighbors gutter lets out right at my basement steps, which I found out about after I first moved into my home years ago and asked them to divert the water so as to not flood my basement again (flooded up to the knee from their one gutter!). They attached a gutter extension and their mom planted a garden and no more flooded basement, but, as it turns out, all the water running like a river on my patio is from that same gutter (mom moved out, no more garden and the extension isn't far enough out in their yard)! I thought all the water was from my property as there is just a cement walkway and about 1-2" of dirt between the walkway and the fence (which they also moved over before I moved into my home - turns out that was moved back 6" too far so I now have about an inch of dirt between the fence and my walkway to work with (and no, they won't move the fence - I've asked them repeatedly to move it back to the property line).

So, as they are now trying to sell their house they are not willing to do anything to help - they've already moved out of state and just want to fix up the house and sell it and to hell with them causing me issues, apparently. Their tree also had overgrown over half of my yard, so I had no sun to dry out the flooded sod that I just put down and they determined the loss of my sod was not from the tree so it was like pulling teeth to get them to cut it back (I offered for them to do it before I cut it all off my property, not caring what it looked like). They cut some of it, but not all as it grew too much and they just really don't care. The issue is, they're flooding my property, including my new grass then the tree is blocking the sun so it can't dry out and I have lost $$ now from planting new sod that is now a mud pool (only planted the sod because they said they'd cut back the tree). I just recently discovered that they cut back on the downspout extender (I'm sure so it doesn't look like crap to potential buyers, as they warned me to do when I sell my home) and that is why my property is flooding so much.

Sorry for writing the whole story, but thought it might alleviate anyone responding with "talk to the neighbors" or "talk to the city" as I've done both and am getting no help from either end so am left to my own defenses.

I am looking for suggestions on what kind of barrier might work to stop their flow of water under the fence. Since they screwed me by moving the fence to far over the property line, there is no room to plant anything or put rocks to flow the water, etc. I am in Chicago so cement will wear away from cold and wetness most likely (and it will look like crap), so am looking for other suggestions. Regular soil built up to the bottom of the fence has not worked as the water is just so much that it wears it away and I'm left with a muddy walkway. Need something that also won't look horrible as I do want to sell my home as well. Is there anything other than regular dirt that might work?

Thank you in advance for any and all ideas - I really appreciate the help!