Contract termination with costs still running.

I, Wynand Human, wanted to upgrade with my Vodacom contract of my mobile device. I was told to pay the outstanding amount of R329.50 to settle the contract in order to upgrade. I paid this amount at the Walk in Centre Port Elizabeth. I then decided to not upgrade and terminate the contract for good. On 30 January 2016 I received a letter from Munnik Basson Dagama Inc. Attorneys requesting the payment of R609.69 as an arrears payment. I am hereby threatened to be blacklisted if I do not pay this amount. I am now confused as to where I stand with this \terminated\" contract. I kindly would like of you to assist me with this dilemma as it will affect my ability to obtain future credit with credit grantors. "