CITIfinancial, Personal Loan — Unnecessary Harrassment by Collection Agents

I have a personal loan running from Citifinancial vide PL No.- 9069029 and till date all the installmetnts have been paid by me. The EMI for the month of July'08 paid to collection agency on 04.07.08 vide slip no.- 90582 ie day before the due date. But I am still getting calls from the collection agency to collect the same. I don't know whether there are some flaws in the working of collections agencies appointed by the Citifinancial or there is big communication gap between the agency and the Citifinancial. Over and above these callers also misbehaves and uses abusive languages.