Are you sure there is no pressure or is it just poor performance?
Pull the rear brake pads and give them a light sand with some sandpaper.
This should clean the pads and remove any glazing.
While they are out, push on your brake pedal lightly and see if the pistons move in the caliper.
If they move then the brakes should work.
You will have to push the pistons back in to refit the pads.
I have cleaned brake pads and discs with prepsol but I don't know how safe this is.
AA
Pull the rear brake pads and give them a light sand with some sandpaper.
This should clean the pads and remove any glazing.
While they are out, push on your brake pedal lightly and see if the pistons move in the caliper.
If they move then the brakes should work.
You will have to push the pistons back in to refit the pads.
I have cleaned brake pads and discs with prepsol but I don't know how safe this is.
AA