I used to rent all my cars through CARFLEXI since 2017. Never got any problem. It's simple and the prices are fair. They are working only with partner that have a good ranking.
Love it. The are the best.
I can see that most reviews are bad but in my experience I never get disappointed.
Prices. Can cancel 48 hours before rental. Money back guarentee.
Don't have but I never had a problem with a car or a partner so my experience was good.