Another look at the issue, this page states that the part number you mentioned is for the Euro UHI too (and would obviously support BT HF). I have not seen this listed on European MB accessory listings. Interesting.
Mercedes UHI and MHI Phone Cradles
Also looks like a different unit from the US version. Odd that this isn't advertised more here, RAZR isn't that uncommon even if it isn't as popular as in the US. Clearly something new to me.