If this booking is not for the immediate future, I'd use AutoSlash or and find a better rate (literally saved $100 last month, which is obscene which you think about that difference on a 2-day rental but it was a small city and a monopoly situation with weekdays to boot, by using it). Then call them back and cancel--and tell them why. If you really want to make a point, you can also complain formally--Elliott dot org, etc. Depends how important it is to you, but I despise sleaze like this.