Empty promises

So I bought a car 2 weeks ago, was promised a R20 000 cash back, 3 days after after purchasing. So 1 week passed and I follow up I'm being told that they need to follow up with the head office, and I get no feedback, so 2 weeks now is passing and I'm still awaiting the cash back, they advised me to sign an indemnity form I don't se why I should when no 1 is getting back to me about my cash back, spoke to my lawyer who advised me I can take the car back a they are in breach of contract not delivering what is stipulated in the contract. I kee emailing the manager he just gives the same answer that he is awaiting feedback from head office, this is against my beliefs as I don't see myself being treated as a customer who brought in money for this company....You guys suck big Time.