PS: I know I saw accounts at 24% interest - but it was APR. If you think about it, if that interest was compounding daily, every fourth day your loan balance would double.
Example: $10k @ 24% per day = $2,400 PER DAY in interest x 4 days = $9,600 interest accrued in four days.
I think what your are paying is an annual percentage rate -
Example: $10k @24% APR= $2,400 per year divided by 12 months= $200 per month in interest + your principal.
What I recommend, if a refi seems undoable, make your payment as far in advance of the due date as possible. The minute your payment post, is the minute whatever principal you paid that month STOPS accruing interest. You would be AMAZED at how adding $10 towards principal helps, too. I'm a fan, personally, of making bi-weekly payments. Cap1 will accept them!
Godspeed!