I need small car for few days and for fun I go to Sixt wab page and make booking smallest and cheapest car what they have in offer (Mazda 2 Aut.).
I want see what they do with my Platinum membership ... we finaly have this car what we booked (Mazda 2) and on question about upgrade I hear form one man 'You are not allowed to free of charge upgrade'. He show me same thing and and this I will check in EU Sixt stations that they have this same info.
This Platinum upgrade policy is big scam in Sixt. In UAE I use different rental company which have better customer support than Sixt.