I tried to get it to learn from the wall controller but it would not see it. I then went to the boiler and the red light was on so i pressed that and the button on the sensor and it connected. It's in a thread further up.
My VR20 has just died and thanks to this thread i purchased a new one from ebay at only £39. Would not connect at first but after referring back to this thread i got it connected via the button on the boiler receiver. Thanks works a treat and saved loads of money.