Grimes Automatic Transmission Repair

i took my van to be fix and was told it would be 1,500 dollars to fix. i was told i could put down 700 and make payments on the rest after it was fix.i pick up my van paid the 700 dollars then about a week later the van was not shifting into gear so i called back and told them it was not working and i was going to bring it back. well i had some other things come up and was not able to get it back to them right away so i parked it in my drive way for a month until i was ready to pay on it so i took it back to them and they got mad at me said it was my fault and did not want to fix it after i already paid them 700 dollars. well it took a couple of weeks to get them to fix it but now they are holding on to my van until i come up with their rest of the payment that i own them witch was not the agreement that we had.so I'm stuck without my car and no way to get to work.i will never take my car back to them and would never every tell any one to take there car there..