Claiming I owe money after two years of silence

On the 19 May 2016, my lawyers, Clientele wrote a letter to MacRobert requesting certain information. NO response was ever received and from the 20th July 2016, when I last received a SMS from MacRobert until today I have never heard from MacRobert again. They are now once again claiming that I owe them money. In the meantime Standard Bank sold this alleged debt to MBD Inc. who is claiming that I owe the money to them.