False advertising from VW on interest rates on their website

VW advertised an interest rate of 5.57% on their website for a new VW Polo Vivo 1.6 Comfortline Tip and now that I have app**** for this offer the interest rate has changed and no one at VW can give me a straight answer as to why I cannot get the advertised interest rate , they are being very ***** and dishonest, this is shameful behavior from such a big motor vehicle manufacturer