general problems of the 2013 Kia Motor Optima Hybrid

The mpg has decreased from 38-40 mpg to 30 mpg since I had the fuel injection service performed. The dealer offers no help. Wish I never had it done. . . . . I get sudden surges of acceleration while driving on the highway. I've had to apply the brakes to slow down. Since this is an intermittent problem the dealer states they cannot help me. The newest issue is when turning the temperature down in the car to low it kicks on the ac. This too is an intermittent problem. I actually showed the service manager the problem yesterday and was able to replicate the issue more than 6 times, first he told me it was normal, then said he would check in to it. Scheduled an appt today for follow up and it is not acting out today. He said I can pay to have the mechanics check it out but since it is intermittent he doesn't think he can help me. Even though he witnessed it yesterday, he says sorry. They treated me like I was making all this stuff up. The dealership is the last place I want to spend my day, especially spending this kind of money. I have been to the dealer several times for the same issues without any answers. They are losing a customer !.

To whom it concerns, I have a great safety concern related to the optima 2013 hybrid braking system. I am not sure if the behavior I am going to describe is typical or defective. When traveling at speed, with the cruise set, I find that any sudden and hard hit to the brakes will activate some type of automatic braking system. The braking system feels like abs and sounds very mechanical however the braking system does not deactivate after I remove my foot from the brake. The system continues to automatically reduces the car to a nearly complete stop (less than 15mph) without me having my foot on the brake. This has occurred multiple times, the most recent was 4/10/14. Earlier today I was traveling 50 mph on the highway, with the cruise set, when it appeared a person was going to walk into the highway. I hit the brakes hard to avoid the pedestrian, who eventually did not enter the road. The situation was not worthy of coming to a complete stop however the automatic braking system I described above activated. I removed my foot from the brake but the braking system continued to bring the car to a speed less than 15 mph. The vehicles behind me, understandably, had to slam on their brakes to avoid me as I could not speed back up until the system resumed to normal operation. Please let me know if this is typical operation or a potential defect. I feel this could be life threatening. Should I have to hit my brakes and this system activates, I could be severely rear-ended. Thank you.