Unprofessional Sales man

Hi. I bought a car October 2018 From the Renault Dealer and I was assisted by a sales man named Denver. All communication was via email, phone both cell and work landline the deal went through I picked up my car, but the registration of the car wasn't sorted to the T on the time of Delivery he assured me that it won't be a problem since the cars registration was still paid for at the time but they will sort it out my registration and send me the new license plates and disc and I gave all documentation. From that day that's was the last time I heard from them, I called in a several times was put on hold or promise to get back to me and still I don't have licenses plates and disc. The sales man is so rude and he is all over the place he told me they had proof that the plates where delivered to me when I asked for proof he told me all sort of different excuses and he didn't have my contact details. Can Ranualt please explain to me is this how you treat your customers tell lies and rob us in the process. Your employees deal with cars and we suppose to drive cars that are road worthy and safe according to the laws of the road. Why do you keep people who are interested on making a quick buck out of us.i paid for those documents so I must be inconvenienced in having to go hold long ques and pay for a service that I had already paid for?