Can’t solve your overall problem but.....
....I can save your flower beds. Same cat was fond of digging my beds and leaving parcels on a regular basis. Solution: get rubber bath mat(s), the ones with holes in to allow the soil to breath. Cut bath mats to into shapes to match soil areas between clumps of flowers. Push dressmaking pins through bath mat pieces and lie pieces between plants, points up. Cover mat shapes with soil to a depth that also covers upstanding pins.
I found it very satisfying on this one occasion to be woken by a cat in the wee small hours - due to its’ blood curdling scream.
Flower beds never molested again.