Could someone please help. Have bought replacement pads but when my son and father went to replace them they could not get the old ones off. I would have got under to look but have done my back in, so need detailed instructions to pass on.

The rear pads are not hard to install
The easy way I found to do it is chock the front wheels with bricks so the car will not roll forward or back.
Jack one side of the back release the handbrake remove the wheel
Before you remove the caliper remove the spring holding the handbrake cable to the handbrake leaver then remove the bolt from the handbrake cable leaver
Undo the top & bottom bolts holding the caliper remove the caliper then the brake pads
Before you replace the pads on the piston in the center of the caliper is an indent
You have to get something to turn the piston back in I used a medium blade screwdriver turn it all the way in make sure you don’t turn the piston the wrong way and it comes out it has to go in
Then on the pad that is closest to the piston it has a raised edge. That edge has to sit in the indent on the piston otherwise the pad will sit out on an angle when you have the indent & raised edge lined up put the pad in then the next pad
Before you put the caliper back on the car where you took the top & bottom bolts out you will see two rubber boots slide the boots back a bit and install some grease
Sit the caliper back install top & bottom bolts install the handbrake leaver you may have to turn the thing that the leaver sits on a little bit to line it up install the bolt back to the leaver
Install the wheel apply the foot brake a couple of times then apply the handbrake a couple of times and that’s it on to the next side hope this helps