Geoff:

That bolt head may be a triple-square head. Looks a lot like a Torx but has 12 "corners" . You can pick triple-square drivers at most auto supply stores.

The tech that repaired my E320 got down to the three screws but it wasn't loose screws, the part they passed through and that held the shroud had broken.

Getting the steering wheel off can be a bear. I think MB uses about a quart of thread locker it.

Hope yours is only loose screws.

Russ A