Bunch of ****** trying to take advantage

Recieved a msg that says my vat on my vehicle will go up to 15 persent. I bought this vehicle a long time ago and the new vat of 15 persent is applicaple only when you buy something from the 1st of april 2018. This is unacceptable as i signed a contract for 14 persent vat with fixed interest rates. This is not what i signed i will not accept this.