only popped up the road and felt when taking my foot off the throttle I was slowing down alot quicker . pulled up at the shops and smoke coming from back brake. not smelling the best and alloy hot. give it 5 and drove home. didnt seem as bad but back discs look slightly rusty like not been used. fronts clean and rust free. advice woyluld be great guys. thanks

Sounds like the brake pad(s) are seized on.

 

Will probably come free with a few taps on the calliper but really could do with taking everything off and cleaning it out to prevent it happening again.

As above, whip pads out and de-rust the pad carriers, check the pads will slide in the carriers easily then refit using a smear of copper slip.

Also check your handbrake mech on caliper is returning fully to the off position, lots get seized up.

The handbrake return springs you can get from VAG dealers are well worth fitting for the sake of under £10 a pair

Had this problem a few weeks ago, had it free'd off and was apparently 'working' again, went for it's MOT a few days later and failed because the rear caliper wasn't working properly, ditched the rears and upgraded to the 256mm rear brake setup, all good since.

Sounds like the calliper is seized