Class A CDL permit renewal (GA)

I have had my Class A CDL permit for a little under a year now, I have already renewed it once. But, I went into the DMV today and I thought I was going to have to take the whole test again, General Knowledge, Combination and Air Brakes. The lady at the DMV said I only had to take the Air Brake test since that was the first one I passed. I didn't study because I thought it would be an easy section since I was so used to driving a truck with air brakes. I ended up failing the section. I went back up to the counter and asked when I come back in is the only test I have to take is the air brake test and she said yes. I just feel like it'll get flipped around and Ill have to take another test like combination since I already did the air brake test. Has anyone had any experience with this because I dont want to focus all my attention into the air brake section and get blindsided?