I've reached out to Sixt reservations in the past, and I wasn't always sure how well informed they were of availability in local branches. In the past at some point I was trying to convert a pay at the counter rental to a prepaid one via e-mail and I got a reply from Sixt which gave me the impression that the information that's on the site takes precedence over what they would write in an e-mail, see below.
Dear codfishcandy,Thank you for your e-mail. Due to the nature of our prepaid rates, we are unable to provide a quote via email as the rates are subject to change based on demand and availability. You can visit us at
www.sixt.com to check the current rate for this prepaid reservation.
We are also available 24 hours a day in our reservation department to assist with a prepaid booking over the phone.
If I were in your shoes I would either:
- Get a reservation through the site, and pre-pay it (once I'm certain it's the best rate I'm going to get) - if you walk up with a prepaid reservation which was booked through their own system they don't really have any other option than honoring it, the way I see it
- Call them (they also have a Belgian number if I recall correctly) to see what they can do, or why you can't get a reservation for the class you desire - if you reserve sufficiently in advance, and it's not high season I can't really see what the problem is (barring special circumstances, of course, such as a major conference or something)
As for why you're running into this; I presume they figure they can earn more by renting their higher end vehicles out for shorter stretches, than having someone rent it for 3 months for a neat rate. Though it would be rather disingenuous if this precludes you from renting them for that.