What can i do with this car, 2002 di?

bought a 2002 di about a year ago. with our credit not being so good got a 15% on it. the car was for $26,000, had a trade in but still had $7000 in it. so that rolled over. the car now is $33,000. i make alitte over $700 payments on this car. i'm in the hole should of walked away than, but at that time of could afford it. now i can't anymore. KBB says it still worth $26000. called the bank that this car was finance through and they said that they cant refinance it since we still owe alot on it and its only worth $26000. called other banks and they said the same thing too. i really want to refinance it but if i can't, what can i do?