Wrong settlement bill

On the 29 July 2015 i called Absa Vehicle Finance requesting my settlement quote and they send it to me the same day and the following day i paid that R59 333.76 that they quoted me. My account was a month in arrears before i requested that letter hence i have asked for a settlement to get rid of all my debts. During the month of August I have received a call from this guy called that my account is 2 months in arrears. They say that they didn't calculate it in the amount of settlement, (really, what is the meaning of settlement letter). Last month i payed R3000.00 and this month is my last payment but now the guy is calling me morning, day and night and its becoming a nuisance!