How lovely, robins are such cheeky chaps
Luckily for the birds here we rarely see a cat in the garden, what about one of those water pistols things? Doesn't do any harm but unpleasant for cats to stay in the line of fire.
I had a robin fledgling in the greenhouse last week for a few days, I saw the parents feeding so hopefully he made it safely to a better location.
Good luck with your robins.