ignition barrel is stuck - G is stuck!

what luck, it was only t'other day that i was reading a fellow member was having problems with his ignition and then my G plays up and has a similar but possibly more serious problem.

the key will not even turn to the third position to start the car. it will click to the first two positions but then will not move a millimeter - it's just blocked.

i've hardly driven the car in the last three months and had to jump start it this morning to get it going. when i tried it later, i encountered the ignition problem and it's not something that a jump start will fix!!

spoke to mercedes, who obviously need to do a proper diagnosis but based on the age of the car ('96) they are guessing that the ignition switch has gone and will cost a fortune to fix (new key, green key(??), new switch, barrel, etc...)

now obviously im not going to green light that sort of work before consulting the pros so my question is, could it be anything else or is there something else worth trying before sending it to mercedes for the real crunch to hit me? has anyone else experienced this problem?? is it worth getting the parts and getting a trusted independent to carry out the works?

lastly - anyone in north london fancing towing me to colindale?? ;) :P