We had astro put down in our garden 2 years ago as we have a small garden and couldn't get grass to grow. The astro has made the space so much more usable, however, our cat uses it as a toilet and just won't be deterred. Every morning we go down and there is a massive pile of crap in the middle of it. I've tried various powders, chilli etc but nothing stops him. It's making the lawn unusable as it's always covered in shit. Any ideas how to stop him?