Urgent braking problem

Hello colleagues, when laymen make…. I tried today to change the brake pads on the rear wheel (Mondeo MK 3, 2.0 TDCI). I worked cleanly according to manual. Unfortunately, when turning back the brake piston I overlooked that the limousine is set clockwise against clockwise and the tournament (which I have) clockwise (left side). So I turned hard against the clock. Now the piston is so far outside that I can not get it turned back in again. What can i I really need help. Of course, the car is in my garage and I could only have it brought to the workshop with the tow truck. I am grateful for every tip. Thomas