Sixt Frankfurt - Question RE web vs phone availability

First time renting from Sixt, I am Hertz President Circle but want to drive a luxury type vehicle out of germany into Italy, a Hertz no no, so I am trying out Sixt, which seems to offer great options, and lots of good stories on FT.

I am renting from FRA for 5 days end of Feb, checked availability and rates online, but wanted to use my Hilton Diamond promo code to (maybe) score an upgrade when I pick up the car and (hopefully) get the "up to 20%" discount. The web showed BMW 5 series automatic available, so I wrote down the web quotes for 5 series auto and 5 series manual, since you cannot use a promo code online I called in, the rate was almost identical to the rate quoted on the web (so much for the Hilton Diamond discount, lets just hope for an upgrade I guess). However, I was told on the phone that no automatics were available, in any class at all, has anyone else encountered this kind of discrepancy?

If I have to drive a manual I guess I will...

One additional question, anyone had success with the Hilton Diamond upgrade in FRA?

Hi TXHolmes

My names Adam and I'm the reservations manager for Sixt in the UK

If you would like any assistance in booking the hire request please just let me know

Alternatively, If you have already placed a booking I will be more than happy to contact the branch to see if we can help out with any further details requested and also look into the automatic transmission request

Please forward the details to [email protected]

I look forward to hearing from you