Not sure if this should be new post, but I have the same "turns once, dies" issue, 1998 ML320. Third or fourth occurrence in 4 years of ownership; always bit bullet to buy $120 new key.

Have only now learned of the 8 key limit.

Local shop unable to determine why keys fail repeatedly. MB North America advises I must replace the Drive Activation Module at about $2200; local dealer insists I need to replace all locks as well, for total near $4000. Anyone have a firm call on who's right?

Hard to fathom MB will let keys fail through no fault of user, then cut off supply of new keys (yeah, fine, for our security...) then hit owner for $2k or more just to have drivable vehicle. Class action suit, anyone? I'm real mad. Steve