How can we do a child support modification in a different state when we cannot afford to travel there?

Case originally heard and ruled in florida. ex-wife disappeared with the 2 children. 4 years letter i got a letter from minnesota saying i was behind on child support and they garnished my wages. my circumstances have changed considerably and i cannot afford the old rate. minnesota says must file modification in florida, as that was where original case was, but florida says minnesota collects so they have to modify. i cannot afford to fly to minnesota. anybody have a few ideas?