I have called and am told all customer billing issues must be through email due to volume. I emailed them 3 times and still have no received response. Below is the email I sent 3 separate times. Hello On 5/13, I reserved a car in Denver. Minutes later I was informed that express-b105579">American Express, along with my GEICO policy, covers damage to rental and I logged online and just cancelled the extra insurance waiver coverage. I see Sixt actually cancelled whole reservation and reserved car again without extra coverage. I was (originally charged $463.98) refunded $264.98 and then charged $463.98 again, therefore costing me an extra $199.00. When I inquired about this at rental counter in Denver, I was told to contact Sixt directly. Could you please look into this and refund the extra $199 charged? Thank you Paul