This bank we had refuses to take our delinquency off the credit report and we can't buy a house...?

We are trying to buy a house and our loan officer says that we can't unless we get we get this bad record off our credit report. We had a company take care of it for us and it still shows. We called the company that took care of paying them off and they said that 2 other banks bought them out while in the process of us paying it off. We called the other banks and their is no record of us. Then we called back the original bank and they said that they won't take it off our credit report because it is not their fault. I'm going to try to dispute the credit agencies but we need to try and close our loan the end of the month, otherwise the sellers may try and find someone else. Is there any other quick suggestions?