I am just spending the 43rd minute in the call center queue, trying to book a Senator Premium Award.
First try: Tried to book on the website, which does not support.
Second try: Tried to book by phone, call center agent said Senator Premium Award were only flights, not upgrades; asked her to check, came back after more than 10 minutes and said she would put it in some "queue" but could not confirm - and could not tell me if/when it would be confirmed. Maybe in a day, maybe just before the flight, maybe never. I asked whether anyone could tell me - answer was no, no one
3rd try: Tried to get through to supervisor, now in call fo another 10 minutes
So, LH voided all my 12 E-Vouchers a few years back, after making them useless in the 1st place. Now I have approx. 3,5 Mio miles which I cannot use even with a Senator Premium Award.
UPDATE
After more than an hour, could not talk with supervisor, center agent talked me into trying to book ("maybe its going to go through") and now the booking is in the queue with a vague promise someone will look into it on Monday.
Maybe this is just a clever move by LH so that SENs with too many miles volounteer to pay 150% of miles, and end up in waitlist anyway