Mercedes: problem with central locking and starting car, car question, prevention system

Question
QUESTION: my husband put the transponder key into the ignition and turned it just to put up window.  when he went out to put the car in garage the key would not engage with he ignition and the steering remained locked,  The central locking has also failed. car can be locked from the inside from the dash switch.  everything else is working fine.  The AA said i need a new key but mercedes say its unusual for both central locking and ignition to fail in the key at the same time.  the steering wheel is also locked.  the manual exterior locking cannot be done.  it just locks drivers door but nothing else.

ANSWER: Fiona,
Sorry, but I have not a clue what type of model and year vehicle you are speaking of.
Thanks
Robert

---------- FOLLOW-UP ----------

QUESTION: Sorry i never realised i left that out.  its a '99 E300TD elegance

Answer
Fiona,
I am sorry for the delay, but my research has turn up nothing. I have seen the key and wheel lock because of a dead battery. Part of the theft prevention system.
I would turn all accessories off, disconnect the battery (-) first then the (+) wait 10 clean the terminals and reconnect in reverse order. The may reset the computer and system.
good Luck
rob