Complain against Hyundai pmb

I'm really not happy with the service I got from Nkanyiso at Hyundai pmb. I went to collect my car today, the car was not ready had to wait for 2hours for them to prepare. Nkanyiso was rude, not helping, not even apologising. He treated me like a stranger. They promised me cash back which I never received. I'm very disappointed and still hurting