I don't know what the program is over there for 5250 units and map subscriptions, so can't say whether 945 should have been made available to you or not, but from what you say, yes -- 945 should have been waiting for you on MyDrive. I'm sure the 'truck' version of that map was already released.
Ah - let me ask just ONE question... you did not, by ANY chance, try to re-use your old email address that was used to register your GO730 for this new unit, did you?
Sounds like you have a good contact on your end, so let us know how this is working out as it goes forward.