Help with magpie please

Hi can anyone help me please. A couple of weeks ago I saw an injured magpie in my mum's garden and two other Maggies were pecking at it. I chased them off and the injured one ran under the caravan and wouldn't let me catch it. I went home and my mum had to chase this pair off all night until dark when they went to bed. I called at mums in the morning and these two maggies were pecking and pulling this poor bird around again, this time I managed to catch it.
I put it in a pet carrier and my mum phoned our local wildlife rescue, explained how busy they were and they will come out when possible or I could care for it myself until it's well and I could go to my vets with it. All vets near me wont treat birds or they want payment for wildlife . I'm currently on sick so don't have the money for vets for something that isnt mine so I decided to take it home and treat it's two wounds that looked like they were caused by the maggies. I put the pet carrier in my dogs cage and cleaned the wounds. They looked sore and swollen but not life threatening . That was two weeks ago. The magpie is strong but still has lump on its foot but I've noticed where the wing was injured still has a lump but no swelling now but it's wing actually has too much movement in the joint.
I was hoping to release it this week where I picked it up but now I don't think it's ready but I also think it had a mate and don't want it to move on but at the same time if the bird won't be able to be released what will happen with its partner. Any help or ideas would be fab. Please dont reply with any nasty messages as I am only trying to help a living creature.