Noisy Rear Brakes when cold/ wet

Hi all,

I had my pads and discs changed on the rear of my fabia vrs around 3-4 months ago, at first they seemed to be ok however over the past week or so the pads are VERY noisy when the car has been standing for a couple of days - notably more noisy when it has rained.

When reversing they make a low pitched noise (the same as if you went to pull off with the handbrake still on) even when not applying the brakes, they also still make a small noise when pulling away slowly having had released the brakes.

After I've driven for around 20 minutes or covered 3-4 miles the noisy seems to be reduced to a minimum - but still exists.

any ideas?

p.s. the brakes fitted were not genuine skoda items but mintex