Mortgage payments

Saxon Mortage took over my loan and notified me my loan would be going up to 1406.00 starting 10/2007. I received payment stubs for that amount and paid it for 6 months. I have never been late since I purchased my house in 2005. In the middle of march I saw on my online account I was behind $12,000.00. Thinking it was a computer error I laughed. I then received letters in the mail stating the same thing. NEVER a phone call. When I called back the stated that I was suppose to be paying 1606.00 a month and all the payment I sent were never applied. Now they are tacking on all the late fees. They never cleared up the error or notified me till 6 months later. April 2008 I am suppose to pay 1830.00, and again the payments stubs are wrong stating 1793.53. Now they won't except any payments . I have made all payment on time and now they are ruining my credit. and--- of course this is an arms loan