Both Colo flush and Shining Teeth and Maxacaiburn offer a free trial of their products for just the cost of shipping (paid for with credit card.) They send a 30 day supply but when you call to complain that you are not satisfied and that they are putting a bunch of charges on your credit card which you did not authorize they tell you that you should have called them within 14 days to avoid charges. I returned the rest of the 30 day trial as well as the unauthorized shipments.They are adding charges under two names, Shining Teeth 1-877-211-8560... read full review »