Jackdaw assistance

A jackdaw was attacked by about 10 or more birds, and fell into my garden yesterday. I took it to the vet, who said that it was ok, and to release it back in my garden. I fed it overnight, and released it into the garden today. After about 10 minutes it flew up onto the roof and was calling out (to the parent birds I suppose), and was then attacked again by many similar looking birds. One was on top of it pecking viciously, so I managed to scare it away. I've managed to retrieve the young bird, and have it safe in a box with some food and water. I've tried calling rescue centres but they're either too far away, don't answer, or advise to let whatever happen.

Can anyone help please?

I live in Paulton, BS39 7XU.