Standard Chartered Blocked Card with not reason

Hello, I am using credit card for years now and never has a situation which stanc has shown me.. stanc card was applied 27-7-2010 used for 2 odd years and in 3rd year even if i was making payment on time there were late charges been applied and after 2 months card got invalidated. I has why and what happen but not answered and said i have complete payment including late charges knowingly that payment was suppose to paid in emi After long chain of mail, calling collections manager nothing got sorted out but bank wanted full payment, after 1 year today i checked my cibil stanc has marked the amount as written off and made 20000 to 40000 amt over due Now I am not a wealthy guy so manage my living via emi I am selected with HDFC bank and they have strict background check and i think my job offer will get rejected because of this default which was not intentionally from my side please help me resolve this issue I have all statement, mail i have sent to stanc for clarification and references as a proof my innocence I dont have much time as background check is under process with hdfc Regards Jaspreet