RENAULT BRYANSTON - MISINFORMATION AND INTURN *******

I recently learnt that the vehicle I purchased on the 5th of May 2018 - said to be a 2018 vehicle is a 2017 model. I would like to know if this is normal for garages to do that, as I would not have known about how to check the year on which the car was made etc, trusting also that you are dealing with a descent Brand, MISINFORMATION and ******* WOULD BE THE LAST THING YOU THINK OF!!! My problem now is, not only have I been overcharged on financing for it, but also for the insurance I have been paying on incorrect information. I did also try to contact the branch on email regarding a billing change just months after my 2 or 3 installments, I got no response. I am really disgruntled at this moment and I do not know who to approach regarding this and also how this can be rectified and compensated if possible!!!!