Sells new vehicles with promises of cash payback

I took my car in for a service. When I got there they told me about their wonderful deal - buy a new car and they will refund my December premium on my old car plus give me 3 months' insurance premiums back - in time for Christmas! I did not want to buy a new car now, but they were very convincing. Well, now 2 weeks later and still no payback. And they are ignoring messages. I am not happy at all!!!