200 km free per day is **** !!

I have use car for 4 days ( 200km free per day). I have used under 500 km for 4 days. I have received invoice that i have been used total 1237km ( 437 km extra charged ) !! I have been CHARGED for unused km.They have charged in my credit card account I have phoned europcar, they spoke very polite and has not come back to us to investigate the problem. I have emailed eurocar and no reply !! I have asked them to proof with satellite tracker with history log book and see how much km i have used. I definitely know that i have not used more than 500 km.