Unresponsive to ***** during purchase.

I have complained numerous times regarding the below and is yet to be responded to. I bought a polo gti from Hatfield VW Bryanston in January 2018, I was told by the dealer that the vehicle is a 2018 registered vehicle only to find out later that it is in fact a 2017 model which makes a difference in purchase price. Is VW not going to do anything about the ***** that was commited during this purchase?