What can I do about my GAP and car insurance?

I got hit Kansas and my car was a totaled loss. I had full coverage and GAP insurance, my GAP said my insurance paid to little and that they(GAP) wouldnt pay for anything. Why do i have to pay out of my own pocket. I still owe 2,200.00 and i just got another car now i have to pay for two cars thats BULLSHIT.