Hi GS
Yes it does happen, not sure how common it is, but i know of someone who was phoned at 7:00 pm at night to be informed by DWP that they had reconsidered their original decision and awarded enhanced mobility and standard daily living, as this person lived on their own and was in the support group of ESA they also were entitled to a SDP which was also backdated to the PIP decision date. The person initially thought it was a hoax phone call as it was after 7:00pm.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems