Please help me!!!?

Ok back in Jan. 2006 i was in a car accident & totaled my car (not my fault) & I decided to go to a dealship & get a car with payments. I'm 24 now (I was 21 then) & I was hoping to build. my credit. I went to a comp. called Drivetime. I didnt have any credit & no co-signer so I knew that it would be hard, I went there because I saw on t.v. that every1 was apvd.. Bad move for me. I got a '05 Hyundai Accent. I put 1,700 down & the guy told me my payments were $192 bi-weekley. He said that they were so high because they do 2 yr. loans. I did it because I could afford it and I wanted good credit & 2 yrs. isn't that long. Well in Mach '07 I couldn't make 1 of my pmts. (first time ever late) I called them & told them I would double my payment the next due date & I was sry. Well my next payment was due on a Sat. so I went in the Fri. b4 & made 2 payments. They took $20 out of my $ & didnt tell me & have taken $20 out of all my payments since. So it shows I havent made a full $ since Feb. HELP