i would also inform the taxi authorities about his drink problem. Not for any sort of revenge/hatred but because any one who drinks and then drives, or drives the next morning whilst still over the limit , is, in my opinion, a danger to all the innocent road users out there, this includes his passengers, other car drivers and their passengers and pedestrians, cyclists etc, whose lives are put at risk by thoughtless drink drivers.
In relation to the post issue, you need to set up your redirection asap, as this takes a few days to come into force. good luck,