Sbi card converted full outstanding amount to emi and emi were paid regularly

Dear sir, I have a credit card from sbi since 5 years, from past few years I am paying minimum payments on date, some time few days later due date but less than 10 days. In 2011 sep, I got sms saying you can pay your outstanding in emi with lower rate of interest and call customer care to avail this option. So I called them they said this offer applicable for you, and asked for 12 checks to pay full outstanding including interest. Since then all emi were paid with out any fail. When I get a cibil report recently, there it mentioned the dpd as 180 since oct 011. I am not sure why its set the dpd as 180, contacted customer care and they said they will correct and allow us 12 working days, after 12 working days I contacted again the they said, until the outstanding gets zero, its not possible to change this. This really hampered my credit history, I have paid minimum payments for long time and bank earned lot of interest on it and finally even they are getting complete amount in emi with interest, but still they caused my credit history gets down. Please help me on this.