this question has cropped up before and we decided that cat craps land mines were the best option but they are not available yet so in the meantime try citrus peel, cats hate citrus
Change houses with the neighbour that owns the moggie and that means they do it in their own garden .Can not suggest as no matter what the cat society would be up in arms about it ..Write to your MP Im sure they have some allowances for it .
Some years ago, I had this problem. Only house in small close without a cat and everyone else's used my front lawn. Tried everything. Smelly deterrents of all sorts - from pet shop, mothballs, etc. eventually Jayes fluid to no avail. Then took up grass and laid shingle. Worse.
Then got a cat of my own. It saw off other cats and (because most cats don't) didn't use the lawn itself.
But. I believe the best solution is actually the sonic cat deterrents you can buy at garden centres.