Disappointed client

I took in my car for service last week Wednesday. Thursday morning I noticed that my odometer was displaying that my car is over due for a service ama it’s on a -122. I called and I was transferred to some guy who apparently did the service on my car. He said he would call me back. It’s 4 days later and the over is now on -400. The promise of being called back was not kept and no one has even tired to assist me. I just want to make it clear that I will hold KIA CENTURION accountable should anything go wrong because of this incomplete serve job.