National Cab Company 1

I took a National Cab from Hobby Airport to the Medical Center. Flat rate of $27 was posted at airport, but cabbie charged me $40. I also found out he took a route that added 4 miles to the drive. I called the cab company 3 times in 24 hours to get a refund, but the company just kept telling me that they could get a hold of the cabbie. Avoid this cab company.