Hello members, Ive had my first Mondeo since September and I now have my first problem

Its a 2006 MK3 Mondeo. The rear passenger side brake caliper is seized on. The handbrake cable is very loose and its my guess its the cable that has seized on the left side for some reason

I am a complete novice and I would greatly appreciate some help to try and fix this myself as I need the car for work on Monday morning

Thanks