My Passenger side one dropped out on Thursday driving home from work, lost on the dual carriageway.
No other damage to car, so luckily didn't hit bodywork.
Order a 9.99 replacement from ebay, will advise when it arrives.
Decided to check drivers side when i got home and it is also completely unstuck, was able to move it up and down with 1 finger.
Removed it, cleaned and refitted with double sided tape.
I do leave the mirror heating on all the time / auto, will switch off now and only put it on when needed.