I have got a electronic cat scar-er
I have tried Garlic Granules spread over the spots they like.
Nothing seems to deter them.
Once many years ago when I worked with a Circus I got Some Lion Poo. It sure did Poo, but it worked.
Any ideas welcome, short of a12 guage.
And no I canr't go back to the Circus.
Thanks.?

Try moth balls around the garden. Works for bunnies.

Cats are finicky about texture, so you just need to find some mulch that they don't like. You can also plant closer together so there are no good spots for them to dig.

Try leaving out some dried orange slices. Supposedly, cats detest the smell of citrus.