How to recover a dog once the councel sold him

My friend had to go away to receive chemo for his bowel cancer his dog decided to go walkabouts the council impounded for 2 weeks then sold him apon his return 2 days after they sold the dog he went to the council requesting the return of his dog and they told him no and its been sold he asked that he would be happy to pay any costs they told to get out .is this legal can they do this to someone they didnt give a toss about the fact he had cancer or anything was just go away can someone help me thank you Chris Knight