They should have done really. Others have been stung by this too, basically as it came into force at the start of this month, any car in the top tax braket that is taxed after April 1st has to pay it, no matter when you ordered it. When I ordered the Zed replacement, they pointed that out to me at the time as a friendly reminder that although I am ordering it before it comes into force, as it will be taxed for the first time after April, it will be applied. You could claim they didnt tell you about it and try to get the money back, but you'd be off on the wrong foot