Best way to respond to an auto insurance adjuster settlement

I'm the claimant in this case. I have been going back and forth with the adjuster on settlement. Each time he has only gone up by 1,000. The last email he sent me when I asked for him to give me reasoning behind his counter offer was that it was based on his medical experience and all of the bills I have sent him. My case is already at 30K in bills/time off work. There is still medical treatment that I have to continue. What is the best way to respond to let him know the reason I'm asking what I'am so that it is enough to cover my futer medical bills also and time off work. Could someone email me a sample letter of how I should put it all together to get it across to him why my settlement offer is what it is.